KENDRIYA VIDYALAYA SANGATHAN

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1 KENDRIYA VIDYALAYA SANGATHAN RAIPUR REGION STUDY MATERIAL (BIOLOGY) CLASS XII

2 Sl No Chapter Pages 1 Reproduction in Organism 3 2 Sexual reproduction in flowering plants 8 3 Human reproduction 14 4 Reproductive health 26 5 Principles of inheritance and variation 33 6 Molecular basis of inheritance 42 7 Evolution 57 8 Human health and Disease 69 9 Strategies for enhancement in food production Microbes in human welfare Biotechnology:principles and processes Biotechnology and its application Organisms and populations Ecosystem Biodiversity and conservation Environmental issues Syllabus,marking scheme, QP blueprint, Question paper 2014 mains and compartmental, newly added topics for march 2015 exam 17(1)-17(36) 18 Key terms to remember chapter (1)-18(11) 1

3 CHAPTER -1, REPRODUCTION IN ORGANISM Age : elephant, rose, dog, butterfly, crow, banana tree, cow, parrot, crocodile, horse, fruit fly, rice plant, tortoise, banyan tree Definition : life span, reproduction, asexual and sexual reproduction difference with example (binary fission, bud, zoospore, conidia, gemmules), vegetative reproduction (runner, rhizome, sucker, tuber, offset, bulb), role of node in reproduction, Sexual reproduction : importance, juvenile phase/vegetative phase (normal and special flowering eg. Bamboo & Strobilanthus kunthiana), oestrus & menstrual cycle, seasonal & continuous breeder with eg. Events in sexual reproduction : Pre-fertilization : A. gametogenesis, iso & hetero gametes, homothallic, monoecious, heterothallic or dioecious pistillate &staminate, hermaphrodite with example i.e. Chara, Marchantia, earthworm, cockroach, sweet potato), meiocyte cell. B. gamete transfer (in algae, bryophyte & pteridophyta with water relation), pollination-self & cross. C. Fertilization : syngamy (zygote), parthenogenesis with example, external and internal fertilization & their importance, Post-fertilization Events : A. Zygote : haplo-diplontic, diplontic. B Embryogenesis : cell differentiation, embryo, zygote & foetus, oviparous & viviparous with example, Ovary & pericarp. CHAPATER : 2 SEXUAL REPRODUCTION IN FLOWERING PLANTS Flower : structure, their parts & importance, floral primordium, flower and their parts (sepal, petal, anther & carpel) Stamens : stamen (anther, connective, filament), monothecous & dithecous, microsporangia vs pollen sac, structure of microsporangium : epidermis, endothecium (role with reason), middle layer, tapetam & sporogenous tissue (pollen develops by meiotic div., tetrad), pollen grain (exine & intine, their chemical composition & role), pollen germination (vacuoles, asymmetric spindle, vegetative & generative cell with difference related to nutrition, 2 & 3 celled stage stage). Allergy: symptoms, reasons with example. Pollen tablet & their uses, viability and conservation with example. Pistal : Megasporangium : monocarpellary & multicarpellary with example, apocarpus & syncarpusl, (Papavar, Michelia), structure of megasporangium/ovule : funicle, hilum, integuments, micropyle, chalaza, nucellus, embryo sac (haploid/diploid) 2

4 Megasporogenesis : MMC (meiosis/mitosis), female gametophyte (embryo sac) : number of chromosome of nucellus, MMC, megaspore, female gametophyte, central cell, egg apparatus (synergid & egg cell), antipodal, PEC in embryo sac -7 celled, 8 nucleate. Pollination : Definition, types : autogamy, geitonogamy, allogamy, xenogamy. Types of flowers : chasmogamous & cleistogamous. Agent of pollination : wind : (well exposed stamens, feathery stigma, number, eg. Corn cogstyle & stigma), water : vallisneria, Hydra, Zostera (marine) process, aquatic plant -water hyacinth and water lily (insect), wind & water nector, colour of petals. Insect : floral adaptation, Amorphophallus, Yucca & moth, Outbreeding devices : self pollination result in inbreeding depression, why?, reason- gametophytic & sporophytic, pollen-pistel interaction & their 3 reason, pollen germination, Artificial hybridization : emasculation, bagging and rebagging Double Fertilization : PEN, syngamy-zygote, triple fusion, PEC, endosperm, embryo, embryo development : globular embryo, suspensor, heart shape, radical, cotyledon, micropylar & chalaza end. Post fertilization events : endosperm (triploid, food nutrition, PEN; nucellar, cellular and helobial with example, cotyledon, scutellum), Embryo : embryology, pro embryo -globular, heart shape and mature embryo of dicot (plumule, cotyledon, hypocotyls, radicle, root cap), monocot embryo (scutellum, coleoptiles, shoot apex, epiblast, radicle, root cap, coleorhizae & their position), epicotyl & hypocotyls, epigeal & hypogeal germination. Seed : albuminous & non albuminous with example, perisperm, testa & tegman, seed dormancy, true & false fruit with example, seed dormancy with their reason, parthenocarpic fruits, seed viability (Lupinus arcticus-arctic tundra, Phoenix dactylifera dead sea), size of seed & their plant eg. Orobanche & Striga (parasitic), Banyan tree seeds, Orchids with reason. Apomixis: definition, eg. Asteraceae & grasses, embryo sac or diploid egg cell Polyembryony : definition, nucellar cell, citrus, 3 reasons of polyembryony, different seed size different shape, CHAPTER 3 HUMAN REPRODUCTION Gametogenesis (sperm & ovum), fertilization, zygote, embryo, blastocyst, implantation, gestation & parturition. 3

5 Male reproductive system: scrotum with temperature, testicular lobules, seminiferous tubules (germ cells/spermatogonia & sertoli cells) & their function, interstitial cells/ leydig cells & their function. Male accessory ducts : rete testis, vasa efferentia, epididymis & vas deferens, their sequence and functions, urethral meatus, penis, glans penis-foreskin, male accessory glands : seminal vesicles(fructose,seminal plasma+sperm=semen), prostate (ca, citrate & acid phosphatase)& one paired bulbourethral glands(cowper s glands)-mucus & lubrication. Female reproductive System: ovaries, oviduct, uterus, cervix, vagina, ovarian stroma-peripheral cortex and inner medulla, infundibulum and fimbriae function, ampula-isthmus, womb-uterus, wall of uterus perimetrium, myometrium & endometrium. Female external genitalia : monopubis, labia majora, labia minora, hymen, clitoris. (virginity, hair, fleshy fold, finger like). Mammary glands: fat, lobes (alveoli), mammary duct, lactiferous ductmilk. Gametogenesis : spermatogenesis :spermatogonia, primary & secondary spermatocytes- spermatidspermatozoa, (spermiogenesis & spermiation), Hormone : hypothalamic-gnrh-two gonadotropin hormone-lh (leydig cell-androgens-spermatogenesis)& FSH (sertoli cells,spermiogenesis). Sperm Structure : head (acrosome,lysosome), middle piece (mitochondria, energy), tail (movement). No million-coitus (40%- slow vigorous motility). Oogenesis : oogonia, primary oocyte (foetal life, Prophase I temporary arrested-birth, childhood,puberty,first polar body), secondary oocyte (second polar body),ovum. Primary oocyte (arrested) surrounded by granulose cells primary follicle, at puberty surrounded by several layers (granulose cells & theca)-secondary folliclesantrum (fluid), unequal division, graffian follicles, ovulation. Menstrual Cycle : menarche, menopause, duration, menstrual flow, lack of menstrual flow, primary-sec follicles, ovarian hormone/ gonadotropin hormones as LH & FSH, their role on 5,14,28 th day, corpus leutam, endometrium. Fertilization & implantation : coitus, insemination, ampullary-isthmic junction, fertilization, zona pellucida, corona radiate and perivitelline space, acrosome,zygote, child male or female? cleavage, blastomere & morula. Blastocyst-trophoblast & inner cell mass. Endometrium, implantation. Pregnancy & Embryonic development: chorionic villi/trophoblast-uterine tissue, placenta, function of placenta, umbilical cord, hcg, hpl, estrogen, progestogens. Relaxin, pregnancy hormone, increase hormone, ecto-meso and endoderm layer & their function, stem cells. Organ development as heart, limb & digits, limb & external genital organ, foetus movement & hair on head, body covered by hair-eye lids separate-eye shed formed. 9 th month pregnancy. Parturition & Lactation : gestation period, neuroendocrine mechanism, foetal ejection reflex, trigger-oxytocinurinary contraction, lactation, colostrums, antibody name, breast feeding. 4

6 CHAPTER-4 REPRODUCTIVE HEALTH Reproductive Health- family planning-1951, First country, RCH, Awareness programme audio-visual, print media, sex education in school, amniocentesis-good or bad, saheli-cdri, STD disease and health, reason of population increase. Polulation exploision and birth control : world population, MMR, IMR, role of RCH & Family planning slogan, marriageable age, problems due to population, Contraceptive methods : Natural-periodic abstinence, withdrawl or coitus interruptus, lactational amenorrhea, Barrier methods-male-condom, female-daphragms, cervical caps & vaults, IUDs,-non medicated by experts as Lippes loop, cooper releasing IUD as CuT, Cu7, multiloaded 375 and their role, IUDs-medicated hormone releasing, role. Oral contraceptive-pills, their role, duration, saheli, progestogen-estogen combination, Surgical methods : vasectomy, tubectomy (vas deferens, fallopian tube).effect of these methods on female. MTP : Govt. of India rule, year, trimester utility. STD/VD/RTI : AIDS, trichomoniass, hepatitis B, chlamydiasis, genital warts, their pathogens name and type. AIDSspread & age group, protection, problems when not aware on time. Infertility : ART, IVF, AIH, AID, ZIFT, IUT, GIFT, ICSI, AI. Full name with using condition. CHAPTER-5 PRINCIPLES OF INHERITANCE AND VARIATION Genetics, Mendelism : first dominant law, second law of segregation-universal accepted, third- independent assortment, their diagrammatic presentation in checker board, 7 contrasting characters (1-stem2-flower,2-pod,2- seed).reason of success. Terms : Filial, contrasting characters, homozygous, heterozygous, allele, gene, genotype, phenotype, monohybrid, dihybrid, test cross, back cross and their utility, punnett square, 5

7 Incomplete dominance : antirrhinum/snapdragon. 4 o clock plant/ Mirabilis, parent colour, progeny colour, phenotype & genotype of F1 F2 generation and result explanation. Co-dominance : multiple allele, incomplete dominance & co-dominance shows by blood groups, possible genotype & blood group of offspring, single gene effect/pleiotrophy on seeds. Inheritance of two genes : genotype & phenotype of F1 & F2 generation. Chromosomal theory : importance, scientist name, how is support mendelism. T.H. Morgan-Drosophila work & importance. Linkage & recombination-procedure & their conditions with percentage. Sex determination : Henking-X body, sex determination in human, Drosophila, insects, birds. Autosomes & sex chromosomes in human, male heterogamety & female heterogamety with examples. Sex determination in human. Mutation : definition, deletion, insertion/duplication. Point mutation & shift mutation with suitable examples. Genetic disorders : Pedigree Analysis : definition, symbols, determination of autosome/sex linked dominant/recessive diseases with upto two generations. Mendelian disorders : Haemophilia : types, symptoms, reasons, precautions. Sickle cell anaemia : : types, symptoms, reasons, precautions, amino acids positions, mutations. Phenylketonuria : types, symptoms, reasons, precautions. Chromosomal disorders: aneupoloidy (trisomy, tetrasomy, monosomy, nullisomy), polyploidy-set of chromosomes. Down s syndrome: reasons, Langdon Symptoms. Klinefelter s syndrome: reasons symptoms, gynaecomastia. Turner Syndrome : reasons, symptoms. CHAPTER: 6, MOLECULAR BASIS OF INHERITANCE 6

8 DNA : DNA length of ssdna, bacteriophage, E.coli, Human. Structure of DNA, backbone, Watson & Crick Model (nucleotide, nucleoside, nitrogenous base, antiparallel, chargaff rule, length, diameter, polarity, OH & phosphate group). Packing of DNA helix : DNA length, diameter, relation of DNA length and base pair, length of E.coli & Human DNA. Histone protein, octamer, chromatin, NHC protein, euchromatin-heterochromatin. DNA is a genetic material : Transformation Principle (Griffth, S-R strain, bacteria, biochemical characterization). Alfred Hershey & M. Chase (1952)-radioactive, phosphorus-sulphur, Process-infection, blending & centrifugation. Differences in DNA & RNA, RNA-catalytic activity, unstable. RNA World: first genetic material why? DNA replication : semi-conservative DNA replication-meselson-stahl experiment, role of CsCl, Taylor et al Vicia faba. Size of DNA, duration of replication in E.coli & human, initiation site numbers, replication fork, DNA polymerase I & III, continuous & discontinuous strand, okazaki fragments, RNA primers, helicase, topoisomerase, single stranded binding proteins, S phase. RNase, ligase. Transcription : changing in base pairs, transcription unit (promoter, structural & termnation), template & coding strand. RNA polymerase, initiation, termination, cistron-monocistronic & polycistronic with examples. Exon & intron difference with example. Process of transcription in prokaryotes :loop formation, role of rrna, mrna & trna, initiation, initiation factor, elongation & termination (sigma & rho factor). Process of transcription in eukaryotes: functions of RNA polymerase I,II &III. HnRNA, splicing, capping, tailng, presence of intron shows RNA world. Genetic code : George Gamow, 20 amino acid, permutation combination-2,3,4-codons 64 how, homopolymerscopolymers Har Govind singh Khurana. Severo Ochoa enzyme (polynucleotide phosphorylase), diagram, Features: triplet, initiation & termination, unambiguous & specific, degenerate, universal, punctuations, universal, initiation & termination codon, mutation in genetic code RAM HAS RED CAP point & frame shift mutation. trna : srna, anticodon loop, amino acid acceptor end, initiator trna, Translation: peptide bond, energy, charging of trna/ amino acylation of trna, UTR regions with examples. Release factors. Regulatin of gene expression: function of regulatory proteins- activator & repressor, lactose & enzyme, lac operon model (z,y,a gene, I,p,o,gene, repressor-inducer), Human genome Project: starts, goal, bioinformatics, costs, HGP-Wellcome trust (UK), contributors, non human model example (plant, insect,nematode, cereal, bacterial, fungi). Methodology: ESTs, Sequence Annonation, YAC 7

9 & BAC, Procedure. Features : bases, average bases, size-largest & smallest with example, gene for protein, repeated sequence, SNP, no of genes lowest & maximum, application in future. DNA fingerprinting: repetitive & satellite DNA(AT/GC rich, small peak, polymorphism), sample, use of VNTR, Procedure. Applications. CHAPTER : 7, EVOLUTION Evolution : earth & life origin, Big bang theory, spore theory, spontaneous theory, oparin & Haldane theoryrequired substances & result, S.L. Millar experiment-procedure, requirement & result, diagram of experiment. Evolution of Life : H.M.S. Beagle, Charles Darwin, Alfred Wallace & their travels finding, meaning of fitness word, book name with year. Evidences of evolution-rock, Dinosaurs-sedimentary rock, age calculation through fossils, Divergent evolution vs homologous organ, Convergent evolution vs Analogous evolution by using two example of each, Natural selection-moth history, pollution indicator with example. Adaptive radiation : Darwin journey- Galapagos island eg. Darwin finches & Marsupials of Australia with their specific features. Biological evolution-bacteria & Mammal evolution-differences, Nature select the fitness- How?, Lamarck theory- use-disuse of organ eg. Giraffe, Thomas Malthus theory & selection with biological evolution. Mechanism : Mendelian factor or gene, Hugo de Vries work on Mutation, minor or large variation, Mutationdefinition, meaning as random & directional, saltation. Hardy-Weinberg Principle : frequency of ales, stable or constant, gene pool is basis of genetic equilibrium, Name of 5 factors of Hardy Weinberg principles (gene flow, genetic drift, genetic recombination, natural selection & mutation) & their meaning. Founder effect, speciation. Plant evolution meaning with zoosterophyllum, arborescent, lycopods, sphignopsida, (hosrse tail), fern, Gnetales with era. Animal evolution thecodents, therapsids, dinosaurs, snakes, sauropsids with era. Period of single cell, jaw less fish, invertebrates, coelacanth-?, Ichthyosaurs & Tyrannosaurs. 8

10 Origin & evolution of human : period, Dryopithecus, Ramapithacus, australopithecies, Homo habilis, Homo erectus, Homo sapien, their brain size & other features. Period of pre historic cave art, evolution of horse. CHAPTER : 8 BIOLOGY IN HUMAN WELFARE Human health & Disease : blackbile, William Harvey, Health affected by genetic disorder, infection, life style, Healthy & disease free meaning, infectious & non infectious disease. Common disease in Human : Type of pathogen, name, vector, symptoms, treatment, transmission mode & test of typhoid, pneumonia, common cold, Ascariasis, filariasis, Amoebiasis, ringworm, Malaria, Dangue and Chickengunia (dual host, life cycle, events as reproduction multiplication, spore, transmission mode & their symptoms). Immunity : definition, types- Innate immunity : 4 type barrier (physical, physiological, cellular & cytocine), Acquired immunity-primary lymphocyte, antibody structure (light & heavy chain, disulphide bond, constant & variable region), Ag-Ab meaning, 5 types of antibody, HMI & CMI- types, differences. Active & Passive immunity : definition, differences with examples. Vaccinatin & immunization- definition, differences, passive immunization, memory, rdna technology. Allergy : definition, allergens, involve antibodies, chemicals (antihistamine, adrenalin & steroid), symptoms. Asthama Auto immunity : pathogens, meanings, disease. Immune system in body : lymphoid organ-primary & secondary, MALT. AIDS : HIV & AIDS, retrovirus, transmission- 4 reason, diagrams (retrovius, RNA core, reverse transcription, factory of HIV, multiplication), symptoms, other disease infection, T lymphocytes & their role, Prevention-WHO, NACO (3 problems). Cancer : meaning, contact inhibition, tumor-benign & malignant, metastasis, carcinogens, oncogenic virus, c- onc/proto oncogenes, cancer detection & diagnosis (x-ray, CT, MRI), treatment- inferteron, & other 2 methods. 9

11 Drug & Alcohol Abuse : meaning. Opoids : Heroin/diacetyl morphine, colour, taste, procedure, source name & useful part, effect on body. Cannabinoids : source, symptoms, part of plant name, their combination (4 names), effect on body. Cocaine : source, name, effect on body, symptoms of Atropa belladonna, Datura, Mental illness (depression & insomnia drug), 4 name of LSD & effect. Tobacco : nicotine, source, effect on body, symptoms (5). Adolescence & Drug / Alcohol abuse : Adolescence meaning, period (5 common symptoms). Addiction & Dependence symptoms, withdrawal syndrome with symptoms. Effect of Drug : person health, HIV, AIDS, Hepatitis, cirrohsis, other symptoms, Prevention & Control : Avoid under peer pressure, education & counseling, seeking help from parents & peers, Looking for danger sign, seeking professional & medical help. CHAPTER: 9 STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION Animal Husbandry : meaning & farm management. Animals : Dairy farm management (name of animals & need, 6 requirement), Poultry farm management : name of animals, 6 management activity, bird flu. Animal Breeding : inbreeding : meaning, inbreeding depression, homozogosity, 6 th generation, how it can be removed. Outbreeding, definition & types, Outcrossing : definition & importance, Cross breeding : definition & Hisardale, Interspecific hybridization : meaning and 2 example (plant & animal). Controlling Breeding experiment : AI, MOET, meaning & their uses. Bee Keeping : definition, uses (2), species, knowledge required for bee keeping (5). Fisheries : meaning, fresh water & marine water fish, differences between Pisciculture & apiculture, difference between blue & green revolution. 10

12 Plant Breeding : meaning, agronomic characters, Procedure : 5 steps with details (collection of variability/ germplasm conservation, evaluation & selection of parents, cross hybridization, selection & testing of superior recombinants, testing, release & commercialization of new cultivars). Agriculture & GDP : wheat- ICWMI, Mexico, Wheat varieties, sonalika & sona kalian, Rice : semi dward IR-8, IRRI, & Taichung Nature I- Taiwan- Jaya & Ratna. Sugarcane : Saccharum barberi & S. officinarum, stem size, east and south India, millets- examples. Plant breeding for disease resistance : crop-wheat, Brassica, cauliflower, cow pea & chili resistant varieties. Mutation : meaning, gamma radiation, eg. Parbhami kranti. Resistance against pest/insect : crop, varieties, insect-pest, Brassica, flat bean & okra. Plant Breeding for food improve quality : hidden hunger, biofortification, Atlas 66, IARI- vitamin A, Protein eg. SCP : meaning, utility, Spirulina, Methylophilus-methylotrophus. Tissue culture: meaning, explants, totipotency, micro propagation, somaclones, meristem, pollen & endosperm culture, somatic hybrids, somatic hybridization. CHAPTER: 10 MICROBES IN HUMAN WELFARE Microbiology : meaning, bacteria, fungi, structure of bacteriophage & bacteria, Microbes in Household Products : LAB, coagulation, milk protein, vitamin B & their rule. Dough-idli & dosa, baker s yeast, Toddy-what?, Swiss cheese & Roquefort cheese-meaning. Microbes in Industrial Products : fermentors, Fermented beverages : yeast, fermentation, distilled (whisky, rum & brandy) or without distilled (wine & beer)product. Antibiotics : meaning, functions, history of penicillin-alexander Fleming, Staphylococci & Penicillium notatum. Other name of antibiotics for plaque, whoooping cough, diptheria, leprosy. Chemicals, Enzymes & bioactive compounds : product & type of microbes Aspergillus niger, Acetobacter aceti, Clostridium butylicum, Lactobacillus. Use of Saccharomyces cerevisiae, lipase (stain of cloth), pectinase & proteases (juice clerify agent), clot buster-use & microbe name, clclosporin A & statin-type, name of microbes & importance. 11

13 Microbes in Sewage industry : sewage, muncipal wase, STPs, treatment : Primary treatment : meaning, sedimentation, filtration, Primary sludge & effluent. Secondary treatment : aeration tank, microbial growth-flocs, BOD-decrease, why?, sediment is activated sludge-use, inoculum, anaerobic sludge digesters-produce gases like co2, biogas, methane, hydrogen sulphide. MEF- Ganga action plan & Yamuna action plan. Microbes in production of biogas : methane bacteria, methanogens eg.- Methanobacterium, rumen, cellulose matter in food, digestion of cellulose in human?, diagram of biogas plant, procedure & labeling, IARI, KVIC. Microbes as Biocontrol Agents: meaning, pollution by insecticide & pesticide, Predation- as a biological control, importance, Ladybird & Dragonflies-aphids & mosquitoes. Bt, Trichoderma, Baculovirus, Nucleopolyhedrovirusshow narrow spectrum insecticidal application, negative impact-nil, IPM. Microbes as a biofertilizers : meaning, importance, organic farming, sources : bacteria, fungi & cyanobacteria their uses & example, Rhizobium, Azospirillum & Azotobacter- their features. Mycorrhiza meaning, Glomus, Phosphorus, symbiotic association- mycorrhiza & Rhizobium why?, Autotropes-Anabaena, Nostoc & Oscillatoria, Paddy field, use-replenish soil & reduce the use of chemical fertilizers. CHAPTER: 11 BIOTECHNOLOGY : PRINCIPLE & PROCESS Biotechnology, Biotechnology & genetic engineering, Principle of Biotechnology : gene cloning, gene transfer, recombinant technology, plasmid, origin of replication, cloning, vector, restriction enzyme. Steps of GM organism (3). Tools of recombinant DNA technology: 1. Restriction enzyme : history, nomenclature, exo & endo nuclease, palindromic nucleotide sequence, sticky & blunt end, diagram representation of rdna technology. Separation and isolation of DNA fragments : gel electrophoresis (diagram labeling-4), EtBr, uses. Cloning Vectors : plasmid, features as ori, selectable marker (transformation), cloning sites (recognition sites, antibiotic resistance site & uses), insertional inactivation with example, structure of vector, Vectors for cloning genes in plants & animals (Ti, Ri, tumor, cancerous, ligation, procedure). Competent Host (Transformation with rdna) : natural, artificial (micro injection, macro injection, gene gun/ biolistics, & their uses). Process of rdna technology : A. Isolation of genetic material (cell wall lysozyme, cellulose, chitinase, chromosome-rnase, Protease, fine thread suspension). B. Cutting of DNA at specific locations R.E., agarose gel electrophoresis, auto radiography (procedure with diagram). C. Amplification of desirable DNA : PCR 12

14 (denaturation, annealing, primers, Taq polymerase, extension, amplified). D. Insertion of rdna into host cell/organism : antibiotic resistant site vs selectable marker. E. Obtaining the foreign gene product : recombinant protein. Bioreactor : definition, culture, cultivation, culture medium, maintaining ph, steam sterilization, motor, foak braker, flat bladed impeller, broth culture, bubbles formation, and their importance. Downstream Processing: biosynthetic phase, meaning, separation & purification, quality control. CHAPTER: 12 BIOTECHNOLOGY AND ITS APPLICATION Green revolution, M.S. Swaminathan, N.Borlog, GMO, GM, Agronomic feature of GM crops, Bt- meaning, name, gene, protein, cryiac, cryiab gene function, toxin crystal & impact on insects. Pest Resistant Plants : nematode, Meloidegyne incognitia, RNA interference (use, silencing of mrna, transposon, sense & anti sense RNA, use). Biotechnology applications in Medicine : Insulin/HUMULIN : proinsulin-insulin, diabetes, allergy, pancreas, two polypeptide, C peptide, Eli Lilly, E.coli, disulphide bond. Gene therapy : meaning, ADA deficiency, symptoms, bone marrow transplantation, use of retroviral vector, lymphocytes, permanent cure. Molecular Diagnosis : use of PCR, ELISA, their basis, probe & their uses. Transgenic Animals : definition, why these produced, Common reason of transgenic animals; A. Normal physiology & development B. Study of disease, C. Biology products (10 example, human protein name, PKU, cystic fibrosis, first transgenic cow name & their importance, nutritional importance) D. Vaccine Safety E. Chemical safety testing. Ethical Issues: GEAE, US patent and trademark, rice, & mango varieties, basmati rice, neem, turmeric, brinjil, 3 issues. Biopiracy : meaning, unauthorized exploitation, Indian Patent Bill, importance. CHAPTER: 13 ORGANISMS AND POPULATIONS 13

15 Biological organization (macromolecules, cells, tissues, organ, individual organisms, population, communities, ecosystem, Biome). Organism & its environment : graphical representation of desert, granssland, tropical forest, temperate forest, coniferous forest, arctic & alpine tundra their annual temperature and precipitation (cm). Major Biome in india (4 name). Abiotic factors : Temperature : variations from equator towards to poles & plains to mountain tops, temp range, 100 o C temp (2 eg.), relations of temperature with area and mango tree & snow leopard. Eurythermal & stenothermal with eg. Water : salinity in parts per thousand eg. Inland water, sea and hypersaline lagoons. Euryhaline animals. Light : photoperiods, biological spectrum & UV spectrum and their utility, red,green & brown algae in water. Soil : weathering, sedimentary, soil development, grain size, water holding capacity, ph, mineral composition of soil, benthic animals. Response to abiotic factors : homeostasis, fitness of living, diagrammatic representation of conformers (%, water & temp changes, osmotic conc., animal in polar reasons), regulators (thermoregulation & osmoregulation, maintaining homeostasis) and partial regulators, migrate and suspend with suitable example. Adaptations : meaning, plants eg. CAM, stomata, leaves spines, stem, Mammals adaptations (Allen s rule, blubber, insulator), physiological adaptations eg. Altitude place as Rohtang pass, altitude sickness, symptoms, problems, Hb., metabolic reactions-100 C & zero how? pressure upto 100 times in sea-problems & adaptations, desert lizard adaptation. Population attributes : meaning, birth rate & death rate, formula, calculations. Age pyramid expanding, stable, declining meaning and importance. Population density, measuring. Population growth : Natality, Mortality, Immigration, Emigration, their meaning. Equation (BIDE), Growth Models : Exponential growth unlimited resources eg. Darwin-natural selection, Logistic growth : limited resources, fittest-survive & reproduce. (graph with equation, also explain e rt, r, K, e). Life history of Variation : r value, sps breed once in life eg, livings produce a large number of small sized offspring and vise versa. Population interaction : meaning and types. Predation (+,-) : eg.tophic level, herbivores, prickly pear cactus in Australia, Pisaster, camouflaged eg. Insect & frog, monarch butterfly-bird, phytophagous insect-plants, thorn in acacia & cactus, Calotropis, commercial product. Competition : Darwin theory, close & unrelated species. Intrinsic rate (r), Gause rule, eg. Abingdon tortoise, Competitive Release eg. Cannell s elegant experiment on Balanus. Gause competitive exclusion Principle-meaning with eg, resource partitioning eg. Mac Arthur-warblers. Parasitism : meaning free lodging & meal, host & parasite both co evolve, eg, Taenia solium (3 features), malaria parasite (endoparasite), ectoparasite-life on human, ticks on dog, female Anapheles mosquito, Cuscuta, copepods, Brood parasitism (meaning & eg.). Commensalism : meaning, eg. Orchid-mango, barnacles whale, 14

16 cattle-egret, sea anemone-clown fish. Mutualism : meaning, eg. Lichen, mycorrhizae, Rhizobium, pollination, figwasp, orchids Ophrys-bee-pseudocopulate. CHAPTER: 14 ECOSYSTEM Ecosystem : Terrestrial (forest, grassland, desert) & aquatic (pond, lake, wetland, river, estuary). Ecosystem structure & function : stratification, components (productivity, decomposition, energy flow, nutrient cycle). Productivity : primary productivity & sec. productivity, NPP & GPP, R. (170 billion ton, 55 ocean). Decomposition : meaning, detritus, detritivores, fragmentation, leaching, catabolism, humification, human & mineralization. Energy flow : PAR, %, Producers, consumers, herbivores vs primary consumers, sec consumers vs primary carnivores, food chain, Difference between GFC &DFC (3), Food Web in terrestrial eco system & pond, standing crop, tropical level vs. food chain. Ecological Pyramids : meaning, energy, biomass and number pyramid, exception, upright & invert pyramid. PP,PC,SC & TC. Ecological Succession : meaning, climax community, sere, bare tocks, lichen pioneer of life, Primary & sec. succession meaning with difference. Succession of Plants : Hydrarch Succession & Xerarch succession, pioneer species, procedure with diagrammatic representation. Nutrient Cycling : meaning, standing state, Biogeochemical cycles, gaseous & sedimentary cycle. Carbon & Phosphorus cycle, difference. Date related to Carbon eg. Fixed c by plants, 49%, 71% & 1%. Litter fall, detritus, rock minerals. Ecosystem service : meaning & example (10), 33 trillion dollar, GNP, Robert Constanza, ecosystem service (50,10,5%-?). CHAPTER-15 BIODIVERSITY AND CONSERVATION Species of ant-20000, beetles, sps of fish & sps of orchids. Biodiversity : genetic (Rauwolfia, rice & mango), Species : meaning, western ghat-amphibian, ecological diversity-different ecosystems. 15

17 Species in India & world : IUCN Billion (12 lac animal & 5 lac plants), Robert May- 7 million global diversity, Invertebrate global biodiversity (insect, mollusca, crustacean & others), Vertebrate (fishes, birds, reptiles, amphibians & mammals), Plant (fungi, angiosperm, algae, mosses, ferns & lichen). India land area 2.4 % but diversity-8.1 %, 12 megabiodiversity, India sps plants & twice animals. Acc. of May-22% discovered, waiting-1 lac plant & 3 lac animal species. Pattern of Biodiversity : 1. Latitudinal gradients : equator to poles, 23.5 N to 23.5S polar area, Colombia-1400 bird sps, Newyork-41 N 105 & Greenland 71 N only 56 sps of birds. India-1200 bird sps, Amazonian rain forest- South America- great diversity as 4 lac plant, 3000 fish, 1300 birds. 427 mammals & 427 amphibians, 378 reptiles, 1.25 lac invertebrates. Evolution of species by speciation, tropical environment-promote niche & constant environment, solar energy. 2. Species Area Relationship : curve between sps richness & area, two equations, frugivorous birds, Z value, steeper slopes. Biodiversity importance to Ecosystem : experiment of Paul Ehrlich-rivet popper hypothesis. Loss of biodiversity : IUCN-2004 : 784 sps extinct (338 vertebrate, 359 invertebrate, 87 plants)-last 500 yrs. eg. dodo, quagga, thylacine & steller sea cow, tigers sps. Threat sps (12% birds, 23% mammals, 32% amphibian & 31 gymnosperms). Causes of biodiversity Losses : Evil Quartet is the sobriquet. 1. Habitat loss & fragmentation (14% earth surface- 6% rainforest, Amazan lung of planet-soyabean & beef cattle, migration due to fragmentation). 2. Overexploitation : meaning, Steller sea cow, passenger pigeon, dodo etc., 3. Alien sps invasion : meaning, Nile Perch,-Lake Victoria-200 cichlid fish, carrot grass, lantana, water hyacinth, Clarias gariepinus. 4. Co-extinction : mutualism & obligatory relation. Need of biodiversity conservation : 1. Narrow utilization : foods, firewood, fibre, products, medicines, 25% from plants, bioprocessing. 2. Broadly utilization : 20% oxygen from Amazon forest, pollination, pollination, bulbul songs, price tag, 3. Ethical use : spiritual, social, philosophical use. Methods of biodiversity Conservation : Save entire forest to save the tiger. In situ conservation : meaning, endemism, hot spot-25+9=34, 3 hot spot in India- Western Ghat & Sri Lanka, Indo-Burma, Himalaya. They cover -2% biodiversity, National parks (90), sanctuaries (448), 14 biosphere reserve. Ramsar sites meaning and importance Sacred Groves : meaning & example of Meghalaya, Rajasthan & Madhya Pradesh. Ex-situ conservation : meaning, zoological park, botanical garden & wild life safari, cryopreservation, seed bank purpose, IVF. Earth Summit & World Summit & their history. 16

18 CHAPTER-16 ENVIRONMENTAL ISSUES Pollution : meaning, pollutants. Environment Protection Act Air Pollution & Control : Structure & use of scrubber & electrostatic precipitator, corona. CPCB- particulate size & harmful to human. Reason of air pollution, disease. Catalytic converter : meaning, use, reason of expansive, unleaded petrol. Vehicular Air Pollution : Case study of Delhi : history, PIL, CNG-2002, Euro II-features, use of road map, Bharat Stage II, Euro III-april 1, Euro IV, Air (Prevention & control) Act-1981, Noise pollution- meaning, db (30,60,70,80,150), symptoms. Water Pollution & Control : Water Act (1974), water bodies, graphical relation of BOD & dissolved oxygen, BOD of tap, partial digested & sewage water, Algal Bloom : meaning, loss of aquatic life eg. E. crassipes, or terror of Bengal. Biomagnification : meaning & effects on aquatic life, Cultural/Accelerated Biomagnification, case study of Arcta, NE of California-Humboldt state university-town people, integrated waste water treatmentsedimentation, filtration & chlorine treatment, heavy metals remains- 60 hectare mashland area-seeded algae, fungi & bacteria, their role, FOAM-meaning. Solid Waste : muncipal waste, sanitary land fills, role of kabadiwalas, role of eco friendly packing. Case study : Ahmad Khan: polybland-fine powder of plastic +bitumen, price 0.04 Rs/kg, hospital waste, e waste treatmentelements. Agrochemicals & their effects : procedure, fungicide, herbicide, eutrophication, case study of organic farming : Ramesh Chandra Dagar- farmer of Sonipat, HKWC-5000 farmers. Radioactive waste : meaning, hirosima-nagasaki, 3 Mile Island, Chernobyl, Japan-2011, Nuclear Dose & health, treatment methods -?, not suitable why? Green House Effect and Global Warming : meaning, gases (CO 2, CH 4, CFC, N 2 O), temperature -18 & +15 o C, El Nino effect, Himalayan caps. Ozone depletion in stratosphere : UV rays, DU unit, ozone & CFC, CL ion as catalyst, Ozone hole, snow blindness-meaning, Montreal Protocol-Canada (1987,1989). Resource Degradation : soil erosion (top fertile soil), deforestation, water logging & soil salinity. Deforestation : meaning, 40% lost in tropics & 1% in temperate, Reforestation. Case Study : 1731, Jodhpur, Amrita Devi Bishnoi Wildlife Protection Award, Chipko movement of Garhwal-Himalaya in 1974, JFM (1980) : meaning & importance. 17

19 Chapter 1: - REPRODUCTION IN ORGANISMS Life Span :Period from birth till natural death.every organism live only for a certain period of time. Reproduction Producing young-ones of their kind, generation after generation. Two types : Asexual reproduction :single parent capable of producing offspring.somatogenic reproduction Sexual reproduction :two parents are invovled in producing offspring. Asexual Reproduction Single parent involved Fusion & formation of gametes is absent Only mitotic divisions Progeny genetically identical (clones) Sexual Reproduction Two parents involved Fusion & formation of gametes is present Involves both (mitosis and meiosis) Progeny with variations (Offsprings.) Modes of Asexual Reproduction : Binary fission: parent body divides into two halves, genetically identical to parent. Eg.-Amoeba Paramoecium. Multiple fission: parent body divides into many daughter organisms. Eg. Plasmodium. Budding: daughter organisms grow from small buds arising in parent body. eg. Hydra, Yeast. Gemmule in sponge. Conidia: non-motile, exogenous spores in chains eg. Fungi (Penicillium). Zoospores: microscopic, haploid, motile structures eg. Algae (Chlamydomonas). Sporulation : Under unfavorable conditions, When the products of multiple fission become individually surrounded by resistant coats, the cyst walls before their release from the parent, the processs is known as sporulation and the encysted products are termed spores. Eg- Amoeba Fragmentation : Filamentous organism divided into two or more individuals eg. Spirogyra, Spirulina. Regeneration: it is the process of renewal, restoration and growth. Eg. Hydra, Planarian flatworm, lizard tail & human liver. Vegetative Reproduction in plants Vegetative reproduction frequently used instead of asexual reproduction, units of vegetative propagation called vegetative propagules. Eg.- runner (Grass, Oxalis), rhizome (ginger), sucker (Mentha), tuber (Potato), offset (Eichhornia), bulb (Onion), Bulbil (Agave). Sexual Reproduction : PHASES OF LIFE SPAN. Juvenile phase: The phase of growth before reproductive maturity. In plants- Vegetative Phase. Reproductive phase: Reproductive maturity. Senescent phase: Phase between reproductive maturity and death. Special Flowering : Bamboo- once in life, generally after years. Strobilanthus kunthiana (Neelakuranji) flowers once in 12 years, (In Sep-Oct 2006,blue stretched mass flowering attract tourists in Kerala, Karnataka and Tamil Nadu). The main events of sexual cycle are: Prefertilization, Fertilization & Post Fertilization. A. Prefertilisation events: a. Gametogenesis : The process of formation of male and female gametes by meiosis (cell-division). Homogamete (Isogamete): - gametes similar eg. Algae Heterogamete (anisogamete): - morphologically dissimilar gamete,male gamete (antherozoid or sperm), female gamete (egg or ovum) eg. Human. Sexuality in organisms : In plants Bisexual term is used for Homothallic and Monoecious plants 18

20 Monoecious : Reproductive organs at different positions in same plant eg. Chara, Maize. Hermophrodite : Reproductive organs at different positions in same animal eg. Earthworm. Unisexual term used for Heterothallic and Dioecious plants. Male and female reproductive-structure on different plants. Flowering plants:male flower (staminate flower) & female flower (pistillate flower) eg. papaya and datepalm. Animals Bisexual term is used for Hermaphrodite animals-eg. Earth-worm, Tape-worm, Leech, Unisexual animals have male & female sexes in separate individuals-e.g. insects, frogs, human beings Cell division during gamete formation: Haploid-parent (n) produces haploid gametes (n) by mitotic division, eg. Monera, fungi, algae and bryophytes. Diploid parent (2n) produces haploid gametes (n) by meiosis division (possess only one set of chromosomes) and such specialized parent cell is called meiocyte or gamete mother cell (2n). Example- Name of organism Meiocyte (2n) gamete (n) Human Housefly 12 6 Ophioglossum (fern) Potato b) Gamete transfer:- to facilitate fusion. Male gametes - motile & female- non-motile, exception few fungi and in algae. Gamete transfer through water : algae, Bryophytes, Pteridophytes & amphibians. Higher plants, pollen-grains are transferred by pollination. B. Fertilization : fusion of male and female gamete. Syngamy : Process of fusion of male and female gamete. Two type of Fertilization: external and internal. EXTERNAL FERTILISATION Fertilisation takes place outside the body External medium is required- water Large no. of gametes produced. Offsprings less protected Eg. Algae, fish, amphibians INTERNAL FERTILISATION Fertilisation takes place inside the body No external medium required Lesser no. of gametes produced. Offsprings- well protected. Gymnosperm, angiosperm, aves, mammals. C. Post -fertilisation events- formation of zygote and embryo. Zygote. Single celled, diploid, vital link between two generations. In fungi & algae, zygote develops a thick walled that is resistant to dessication and damage. Haplontic life cycle- zygote (2n) divides by meiosis to form haploid (n) spores. Diplontic life-cycle- zygote (2n) divides mitotically, develops into embryo (2n). Embryogenesis: development of embryo from zygote by cell division (mitosis) and cell differentiation. On based of Zygote development, animals are grouped into two types- Oviparous Animals They ley fertilized or unfertilized egg. Fertilized eggs have calcareous shell Development of embryo outside female body Less chance of survival. Viviparous Animals They give birth to young ones. No calcareous shell Development of embryo inside female body More chance of survival. 19

21 Eg. Reptiles and Birds Eg. Mammals Cell- division increases the number of cells in the developing embryo Cell differentiation - groups of cells undergo certain modifications for the formation of different kinds of tissues and organs. In flowering plants- zygote formed inside ovule. Changes occur in flowering plants: Sepal, petals, stamens, Fall off Zygote Primary endosperm nucleus Synergid, antipodal cells Ovary Ovule Ovary wall Outer Integument Inner Integument Embryo Endosperm (3 N) Disintegrate Fruit Seed Pericarp (epicarp + mesocarp + endocarp) testa tegmen Parthenogenesis: Female gamete develops into new organism without fertilization. eg- Honey bee, turkey, lizard, rotifers (Protozoans). Seedless fruits formed by parthenogenesis Clone: A group of individuals of the same species that are morphologically and genetically similar to each other & their parents. QUESTIONS Chapter 1: REPRODUCTION IN ORGANISMS Q) What is meiocyte? Ans) It is the gamete mother cells which undergoes meiosis. Q) Why is date palm referred to as dioecious? Ans) In date palm the male and female flowers are present in different plants. Q) What is special in flowering in bamboo? Ans) Bamboo flowers only once in their life time generally after years. Q) Define clone? Ans) It is a group of individual of the same species that are morphologically and genetically similar. Q) What is vegetative propagule? Ans) The units of vegetative propargations that gives rise to a new plant is called vegetative propagule. Examples: Runner and rhizome. Q) Digramatically represents asexually reproduction in yeast? Ans) See Figure 1.2 (page-5) Q) Cucur bit are called monoecious. Justify? Ans) They have male and female reproductive structures in different flowers. Q) If chromosomes number in meiocyte in rat, elephant and rice is 42,56,24 what will be the chromosomes number in theier gamet? Ans) Rat 21, elephant 28,rice 12 3 marks Q) Why higher organisms have resorted to sexual reproduction in spite of its complexcity? Ans) 1. It brings about variations. 20

22 2. Variation helps in better adaptation in nature. 3. Variation is the basis of evolution. Q) What is parthenogenesis. Give Example? Ans) Development of a new individual from an unfertilized egg is called parthenogenesis. It is simpler easier and rapid mode of replication. But there is no chance of any variation. So it does not play any role in evolution. Eg.- Honey bee and some lizards Q Mention the reason for difference in ploidy of zygote and primary endosperm nucleus in angiosperm Ans Zygote is formed by fusion of haploid male gamete and haploid egg so it is diploid. Whereas the PEN is formed by fusion of haploid male gamete with two haploid polar nuclei so it is triploid.. 5 Marks. Q) What are vegetative propagules. Name any four of them and give example? Eg.- rhizome of ginger, leaf bud of bryophyllum, bulb of onion, offset of pistia. HOTS. Q)Amoeba is immortal. Explain? Ans) Amobea has no natural death. It undergoes binary fission and forms two new daughter cells. Q) Which is the first diploid single cell which begins life? Ans) Zygote. Q What is the fate of zygote in organism which show 1 Haplontic life cycle 2Diplontic life cycle Ans In haplontic life cycle zygote undergoes meiosis during its generation In diplontic life cycle zygote divides mitotically during embryogenesis Q) What type gamete are formed in staminate and pistillate flowers? Ans) Pollen grains and egg cell respectively. Q) Name the organisms with respect to their sexuality? i) Monoecious animal ii) Dioecious animal iii) Monoecious plant iv) Dioecious plant Ans :- i) Earthworm ii) Cockroach iii) Chara iv) Marchantia. 21

23 8-1 CHAPTER- 2 Sexual reproduction in flowering plants 22

24 CHAPTER 2 SEXUAL REPRODUCTION INFLOWERING PLANTS FLOWERS : modified shoot, Site of sexual Reproduction. Male and female reproductive organs are borne on flowers. PARTS OF A FLOWER: Four whorls- Calyx (sepals): green in colour, protects the bud. Corolla (petals): colourful, attracts insects for pollination. Androecium (Male reproductive organ), Gynoecium (Female reproductive organs) Calyx & corolla : accessory whorl. Androecium & gynoecium : Essential whorl. Male Reproductive Organ Androecium consists of Stamens. Stamen consists of anther, filament & connective (when anther is bilobed) Anther : bilobed (two theca) has 4 microsporangia. Refer fig. 2.1 of NCERT (L.S. of a flower with different parts) MICROSPOROGENESIS: The process of formation of micro spores from pollen mother cell (2n) through meiosis. Microsporangium is 4 layered: Epidermis : single outer layer Endothecium : dehiscence of anther Middle layer : 2-4 layered,crushes when sporogenous tissue mature. Tapetum : dense cytoplasm & multinucleate, Nourishes the developing pollen grain & formation of pollen wall, Microspore mother cell (2n) Meiosis Microspore (n) Mitosis Pollen grains (n) Pollen grains : Male gametophyte, size µm. Two layered :- Exine : Exine is made of sporopollenin.(hardest natural substance). Intine : Intine is made of cellulose and pectin. Pollen Maturation : Mature pollen grains have two cells large vegetative cell & small generative cell. Generative cell forms two male gametes by mitotic division. Pollen grains shed in 2-celled / 3celled stage (See Fig 2.5 a and b page 23 NCERT) Gynoecium / carpel (the female reproduuctive organ) (Structure of anatropous ovule) / Megasporangium Apocarpus : free carpel Syncarpus : fused carpel Monocarpellary : single carpel Multicarpellary : Many carpel. Each Carpel consists of ovary, style & stigma. Ovules are attached to ovary by placenta. Funicle stalk of ovule Hilum, a region where funicle is attached Integuments cover embryo sac. Micropyle a pore for entry of pollen tube. 23

25 Embryo Sac : Female gametophyte Nucellus : it covers embryo sac, seed up to maturation. Megasporogenesis The formation of megaspore from the megaspore mother cell MMC (2n) is called megasporogenesis. In megaspore tetrad, 3 degenerate & one functional megaspore develops into female gametophyte (embryo sac). Embryo sac (Polygonum type) - 8 nucleate & 7 celled. Synergid cell have special cellular thickening at the micropylar tip called filiform apparatus,which play an imp. role in guiding the pollen tube into the synergid. MEGASPOROGENESIS POLLINATION transfer of pollen from anther to stigma. Agents of pollination air, water, insect.bat,bird,man. Self pollination (Autogamy) Auto gamy (Same flower) Transfer of pollen to stigma Geitenogamy Different flowers same plant Cross pollination (Hetrogamy) Xenogamy (different flowers on different plants of the same species) 24

26 Autogamy : Chasmogamous flower-exposed anther and stigma. eg- Viola, Commelina, Oxalis. Cleistogamous flower : anther and stigma-closed. It assured seed set in the absence of pollinator. eg- Viola, Oxalis. Adaptation for pollination Wind pollination Water pollination Insect pollination Pollen grains light, non-sticky, colourless, well exposed stamens, feathery stigma & numerous flower. Pollen grains protected by mucilaginous covering, long stalk & long coiled style. Colorful & showy flower, high fragrance, produce nectar, sticky pollen grains & stigma. Special type of Pollination : A. Amorphophillus (flower height-6 feet), provides safe place for lay eggs of insects. B. A moth deposits eggs in the locule of ovary of Yucca plant & inturn pollinates Yucca. Out Breeding Devices : to promote cross pollination because self pollination results in inbreeding depression. Heterostyly : Different size of style & stamens eg. Primula (Pin & Thrum flowers) Herkogamy : Anatomical barrier eg. Calotropis procera. Self Sterility : Pollens donot germinate on stigma of self flower eg. Malva Protoandry : anther mature before pistel eg. Hibiscus rosa sinensis. Protogyny : Pistel matures before anther eg. Aristolochia Self Incompatibility : Pollen & stigma of same flower & same plant rejects to each other. Pollen Pistel Interaction : Stigma have the ability to recognize the right type of pollen it rejects the pollen grains of other species & also the incompatible pollens of the species. Artificial Hybridization : it is a major approach to crop improvement programme. It is achieved by - i) Emasculation: Removal of anthers from the flower bud of a bisexual flower before the anther dehisces using a pair of forceps. ii) Bagging - covering the emasculated flowers with a bag of suitable size to protect them from contamination with unwanted pollen. iii). Rebagging : Mature pollen grains collected from anther of the male plant & dusted on stigma, and the flowers are rebagged and the fruits allowed to develop. Double fertilization Fertilization is the process of fusion of male & female gametes (n+n) to form a diploid (2n) zygote. First fertilization : Fusion of male gamete with egg is called SYNGAMY & develops embryo (2N) Second fertilization: Fusion of polar nuclei with 2 nd male gamete is called TRIPLE FUSION & develops PEN (3N). Since two types of fusions, syngamy & triple fusion takes place in an embryo sac the phenomenon is termed double fertilization. C. Post fertilisation changes: 1. Endosperm : 3 type of endosperm development i). Nuclear : PEN successive nuclear divisons to give rise free nuclei eg. Cocus, Areca catechu (betal nut). ii). Cellular : Wall formation occurs after every division of PEN eg. Annona squamosa, Adoxa. iii). Helobial : both type of development is present (nuclear & cellular) eg. Monocots. Embryo development : 25

27 1. Zygote divides by mitosis into suspensor & embryo cells 2. Suspensor cell forms a globular basal cell which remains embedded in the endosperm & a multicellular suspensor bearing the embryo 3.Globular embryo becomes heart-shaped & then mature embryo with radicle, plumule & Cotyledons. Scutellum : Monocot embryo DICOT EMBRYO MONOCOT EMBRYO - GRASS Difference between : EPICOTYL Area of embryo axis between the plumule & cotyledonary node. In hypogeal germination epicotyls elongates & seeds remains underground. COLEOPTILE Covering of plumule in monocots. Coleoptile breaks grain covering and elongates. It turns in green. It protects plumule during emergence from soi. PERISPERM It is a part of seed. It is Remnant of nucellus. Dry No significant importance Eg. Black pepper, beet HYPOCOTYL Area of embryo axis between the radicle & cotyledonary node. In epigeal germination, hypocotyls elongates & push the seed out of soil. COLEORHIZA Covering of radicle in monocots. It breaks grain covering but stop further growth It remains inside soil. No such function. PERICARP It is a part of fruit. It is overy wall (epicarp, mesocarp & endocarp). Dry / fleshy Protection, dispersal and nutrition of seed. Eg. Mango 26

28 TRUE FRUITS True Fruit develops only from the ovary, e.g. mango, tomato Albuminous Seed Seed retains endosperm as it is not completely used up during embryo development. Eg. Wheat, maize, barley, sunflower, castor. Apomixis It is a asexual reproduction which mimics sexual reproduction where seeds are formed without fertilization from diploid egg cell and other cells of nucellus. FALSE FRUITS False Fruit develops from parts of the flowerother than the ovary e.g. apple, peach etc Non albuminous seed Seeds do not retain endosperm as it is completely utilized during embryo development. Eg. Pea, grountnut. Parthenogenesis Development of haploid female gamete (egg cell) into an adult without fertilization. Significance of fruit formation : The fruits protect the seeds from unfavorable climatic conditions. Both fleshy and dry fruits help in the dispersal of seeds to distant places. source of many chemicals like sugars, protein, oil, organic acids, vitamins and minerals. provide nutrition to the developing seedlings. Importance of Apomixis : Since apomictic seed are produced asexually so they maintain their agronomic characters. So they are used in hybrid seed industry, floriculture, horticulture. Polyembryony- Occurrence of more than one embryo in a seed is called polyembryony. It is due to formation of more than one egg in embryo sac, formation of more embryosac, synergid cell, integument and nucellus cells may also develops into embryo. e.g.orange, lemon, groundnut, mango, onion etc. 27

29 Chapter-3 HUMAN REPRODUCTION Events of Human Reproduction Gametogenesis : formation of gametes. Insemination : Transfer of sperm in female genital tract. Fertilization : fusion of sperm and ovum. Implantation : attachment of blastocyst with uterine wall for further development. Gestation : Embryonic development Parturition : Delivery of the baby. The Male reproductive system Penis : a. Urination b. Sexual intercourse c. Corpus cavernosum- spongy tissue that fills with blood to make penis erect d. Glans- the head, end of penis e. Foreskin i. Covers glans, ii. May be removed surgically in an operation 2. Scrotum a. Located behind penis b. Contains two testes c. Temperature sensitive (Sperm must be made in cooler conditions i.e, C lower than body temperature) 3. Testes a. Sperm is produced by the seminiferous tubules due to FSH b. Testosterone is produced by Leydig cells due to LH Sertoli cells : Provide nutrition to developing germ cells. Interstitial cells / Leydig cells : Synthesize & secrete testicular hormone called androgens. (Refer Fig. 3.2, page no.-44 NCERT) ACCESSORY DUCTS : Epididymis: Stores sperm until they have matured. Vas deferens: Tube that leads from the epididymis to the urethra. Many sperm cells are stored here too. ACCESSORY GLANDS : Prostate gland: Seminal Vesicles: Cowper's gland: Provides an alkaline fluid that can protect sperm from harsh vaginal acids. Produce food for sperm. Food "Fructose" Produces clear lubricating fluid 28

30 SPERM SEMINIFEROUS TUBULES Head : It contains a elongated haploid nucleus, covered by acrosome. It filled with hydrolytic enzymes to dissolve the membrane of ovum for fertilization. Neck : It contains two centrioles helps in first cleavage division of zygote. Middle Piece: contains numerous mitochrondria which produce energy for movement of tail that facilitate sperm motility essential for fertilization Tail : helps in Sperm movement Spermatogonium : it is diploid contains 46 chromosomes. Primary Spermatocyte (2n): it complete 1 st meiotic equal division (reduction) & forms 2 secondary spermatocytes. Secondary spermatocytes : it is haploid, undergo the 2 nd meiotic div to produce four equal haploid spermatids. Spermatids : They transformed into spermatozoa (sperms) by the process called spermiogenesis with the help of FSH. Spermiation : After spermiogenesis, sperm heads become embedded in the sertoli cells and finally released from seminiferous tubules by the process of spermiation. The Female Reproductive System : Ovary: Each ovary contains immature ova (eggs) in follicles. ii) Females born with lifetime supply of eggs (250, ,000 in each ovary) iii) Ovaries release ovum -. Almost all ova degenerate between birth and puberty. iv) Approx. 400 eggs will be ovulated over woman's life. v) Egg is the largest human cell. vi) Ovaries are located lower abdomen. 1 left and 1 on the right. Fallopian tubes i)two thin tubes attached to the upper sides of uterus ii) Tubes terminate near the ovaries but are not attached iii)"fimbriae" are finger-like structures on the end of each tube iv)tubes conduct egg to uterus by use of small hairs called "cilia" v)fertilization of ovum takes place in the ampullaryisthmic junction of the fallopian tubes. Egg viable for only hours after ovulation. Uterus: i)pear-shaped organ located in lower abdomen. ii)muscles(myometrium) stretch to allow baby to develop. Oxytocin starts labor contractions. iii)lining of uterus (endometrium) thickens with blood-rich tissue due to progesterone. iv)endometrium supports embryo/fetus during growth. v)placenta It is the interface between baby and mother. If not pregnant, lining breaks down and is discharged from body through vagina. This is menstruation (period). vi)cervix connects uterus to vagina. Like a door that opens during ovulation. Cervical mucous closes the door at all other times. (Refer Fig. 3.3b, page no.-45 NCERT) 29

31 EXTERNAL GENITALIA: Vagina (Birth canal) : Menstrual blood leaves the body, Organ of intercourse, Muscular stretches to allow a baby to grow Vaginal opening partly remains closed by thin membrane of tissue called hymen. May be stretched or torn during any physical activity or first intercourse. Cervix: Located at inner end of vagina, Opening of uterus into vagina, Mucous prevents bacteria and viruses from entering uterus, Lets sperm into uterus after ovulation Where baby also passes through during vaginal birth Labia: 2 layers of skin, which fold over the opening to vagina and urethra ii) Inner labia (labia minora) iii)outer labia (labia majora) Pubic hair grows on outer labia Clitoris: Small organ, 5 to 10 millimeters long; Located at junction of inner labia near front of body Contains erectile tissue& sexually sensitive. Mons pubis :Cushion like fatty tissue covered by skin and pubic hair Gametogenesis & its hormonal regulation : FSH and LH from the pituitary: FUNCTION / PRODUCTION Hormone In Females In Males FSH Controls LH Controls Eggs + Estrogen (Follicular development) Ovulation + Corpus Luteum Spermiogenesis Testosterone (Spermatogenesis) Differentiate between: Spermatogenesis and Oogenesis : Spermatogenesis Produces male gametes (sperm) occurs in the seminiferous tubules (in testes) occurs throughout life after puberty may produce 3,00,00,000 per day Primary spermatocyte divide equally to form two similar secondary spermatocytes One spermatogonium produces 4 functional spermatozoa Oogenesis produces female gametes (oocytes) occurs in the ovaries occurs after puberty until menopause humans normally produce one oocyte during each ovarian cycle Primary otocyte divide unequally to form one large secondary oocyte and a small polar body An oogonium produces one functional ovum and 3 non functional polar bodies REFER fig.3.8 page : 49 NCERT. 30

32 OVULATION : From Primordial Follicle to Tertiary Follicle Primordial follicle:the surviving primary oocytes, at birth, are surrounded by thin, single layers cells of socalled follicular epithelial cells. Primary follicle : The primordial follicles while developing into primary follicles the follicular epithelium that surrounds the oocyte becomes iso- to highly prismatic A Primordial follicle B Primary follicle 1 Oocyte 2 Follicular epithelium 1 Oocyte 2 Pellucid zone 3 Stratum granulosum 4 Theca folliculi cells Secondary follicle Secondary follicles with follicular epitheliums encompassing multiple rows are formed called the stratum granulosum. Pellucid zone, between the oocyte and follicular epithelium becomes visible. Tertiary follicle A well-developed net of capillaries in the theca interna. Antrum a fluid filled cavity develops The theca layer organized into Theca internal & Theca external Refer : Fig. 3.7 page 49 NCERT. 31

33 MENSTRUAL CYCLE : Follicular phase (Proliferative phase ) and Luteal phase (Secretory Phase) Proliferative phase Follicular phase Stage of repair and proliferation It extends from the end of menstruation to ovulation LH and FSH increases Estrogen level increases Estrogen is secreted by Graffian follicle Secretory Phase Luteal phase Prepares endometrium for implantation It extends after ovulation to menstruation LH is high (LH surge) Progesterone level increases Progesterone secreted by corpus luteum Flow diagram of Menstrual Cycle Menstruation Repair of the endometrium Follicular Phase FSH/Estrogen Ovulation Due to LH Thickening of the endometrium MENSTRUAL CYCLE: Ref. Fig. 3.9 page 50, NCERT Luteal Phase LH/Progesterone Breaking down EMBRYO DEVELOPMENT IN HUMANS MENSTRUAL CYCLE Zygote The single cellthat results from fertilization of an ovum by asperm. Morula Blastocyst *The morula (little mulberry)i Solid ball (16 64 cells). Morula arises from mitotic (cleavage) divisions. The blastocyst is a liquid-filled ball of cells. Occurs around 5 8 days after conception. Implantation in the endometrium occurs at this stage. Embryo Human considered an embryo from implantation until about 8 weeks after conception. 32

34 Foetus 8 weeks after conception until birth. Transport of ovum, fertilization and passage of growing embryo through fallopian tube. Fate of three germ layers Ectoderm Mesoderm Endoderm Nervous system Skeleton Digestive tract Epidermis of skin Muscles Respiratory system Circulatory system Liver, pancreas Gonads Bladder Mnemonics ( Remember technique) Tubules in male reproductive system SEVEN UP Seminiferous tubules Epididymis Vas deferens, Ejaculatory duct (Nothing) Urethra Penis Menstrual Cycle FOL(d) M(a)PS Ovarian cycle: Follicular phase Ovulatory phase Luteal phase Menstrual cycle: Menstrual flow, Proliferative phase Secretory phase 33

35 Trophoblast and Inner cell mass : Inner cell mass : Inner cell mass contains certain cells called stem cells which have the potency to give rise to all the tissues and organ. Trophoblast : Layer get attached to endometrium. It is ssurrounded by finger like projections called chorionic villi after implantation. Blastocoel :Cavity of blastocyst that contains inner cell mass. Pregnancy and embryonic development : Placenta : Chorionic villi & uterine tissue become interdigitated with each other and jointly form a structural & functional unit between developing embryo & maternal body. It provide antibodies to foetus (IgG). Function : supply of O2 & nutrients to embryo and removal of CO2 & excretory products from embryo. Act as a endocrine tissue & produce hormones like human chorionic gonadotropin (hcg), human placental lactogen (hpl), estrogen. Pregnancy hormone : Relaxin These hormones essential for fetal growth and metabolic changes in mother and maintenance of pregnancy. FETUS DEVELOPMENT MONTH / PERIOD First month Second month First Trimester (Three month) Fifth Month Second Trimester (Six month) Eight month Third Trimester (Nine month) CHANGES IN FETUS GROWTH Heart development & starts heart beat. Limbs & digits Organ system develops. Eruption of hair & foetal movement. Body covered with hair, Eye lids separates, eye lashes formed. Testis descend into scrotum. Development of body mass & at last parturition. Lactation : In the influence of hormone Prolactin (hpl) & progesterone, mammary glands starts producing milk. 34

36 Colostrum : thick & yellowish milk consist of antibodies (IgA) & develops immunity to protect from pathogens to infant. TERMS TO REMEMBER Acrosome- the part of a sperm cell that contains an enzyme (This enables a sperm cell to penetrate an egg.) Amniotic sac-fluid-filled membrane or sac that surrounds the developing embryo while in the uterus.(protects baby from hard shocks, keeps it at a constant temperature. ) Blastocyst = blastula = early stage of an embryo; a liquid-filled sphere whose wall is composed of a single layer of cells; during this stage (about eight days after fertilization) implantation in the wall of the uterus occurs. Cervix- lower part, or neck, of uterus. (Opening to the uterus.) Clitoris-small, sensitive organ in front of the vagina Coitus-synonym for sexual intercourse Conception-fertilization of an egg cell by a sperm cell Corpus Luteum - After ovulation, this crater-like structure produces progesterone and estrogen. The corpus luteum is the old RUPTURED GRAFFIAN follicle. It means yellow body. Cowper's glands - 2 glands that secrete an oily liquid, which cleans and lubricates the urethra of the male Egg cell-a female sex cell (female gamete or ovum or secondary oocyte ) Ejaculation-the discharge of semen from the penis Embryo-the unborn child developing in the uterus between the second and eighth weeks of life Endometrium - the lining for the uterus site for blastocyst implants and develops. Epididymis-the tightly coiled tube at the back at each testis that holds newly created sperm (each epididymis is like a nursery where sperm mature and learn to swim.) Erection- condition of penis when it fills with blood and becomes firm, enlarged, and erect. Fallopian tubes -tubes leading from each ovary to the uterus. Tubes carry the egg from ovary to the uterus. Fertilization occurs here. (Also known as the oviducts.) Fimbria - A fimbria (plural fimbriae) Latin word, literally means "fringe." a fringe of tissue near the ovary leading to the fallopian tube Fertile- able to conceive a child Fertilization union of sperm and egg.conception. Fertilized egg- egg after sperm has united with it. Zygote. Fetus-unborn child developing in the uterus after the first eight weeks of life Follicle - In ovaries. Each holds and nourishes an egg until ovulation. Nest. Becomes corpus luteum after ovulation. Foreskin A sheath of skin that surrounds the penis. Follicle Stimulating Hormone - secreted from pituitary gland in both men and women. In women, FSH promotes the development of eggs and estrogen. In men, FSH promotes the development of sperm cells. Fraternal twins-babies that develop from two eggs, each fertilized by a sperm cell; may or may not be of the same sex Gamete a sex cell. Sperm cells and egg cells are gametes. Genitals-the reproductive or sex organs, especially the external organs Germ Cell- egg or sperm cell.gamete. In humans, germ cell contains 23 chromosomes Hormones-chemical substances produced by the endocrine glands; they act in other parts of the body and affect maturation, growth, and behavior; LH, FSH, GH, Testosterone, Estrogen, Progesterone are all hormones. Hymen-a thin bit of tissue, or membrane that may partially cover the opening of the vagina Identical twins-babies that develop from a single fertilized egg that separates into two halves; identical twins are always of the same sex Labia-two folds of skin surrounding the entrance of vagina Labor-the muscular contractions that expel a baby from uterus during childbirth Leydig Cells when prompted by LH, Leydig cells create testosterone. 35

37 LH - Luteinizing Hormone - Secreted from pituitary gland, causes ovulation and formation of corpus Luteum in women. In men, LH causes Leydig cells to produce testosterone. Menstrual cycle - periodic building up and sloughing off of lining of uterus approximately every twentyeight days Menstruation-the periodic discharge of blood and waste material (unfertilized secondary oocyte / ova and the degenerating endometrium lining) from the uterus Miscarriage- expulsion from the uterus of a fetus before it is developed sufficiently to live Also called spontaneous abortion Myometrium muscles of the uterus that stretch to accommodate the growth of the baby. These muscles contract during labor and push baby out. Orgasm-the peak of sexual excitement when the male ejaculates semen, Ovary- female sex glands; they produce egg cells, estrogen and progesterone. Ovulation-the discharge, or release, of an egg cell / secondary oocyte from the ovary Ovum-scientific name for an egg cell / secondary oocyte Oxytocin - hormone, released from the pituitary gland, stimulates contractionof the myometrium of the uterus during labor and facilitates ejection of milk from the breast during nursing. Penis-the male sex organ through which sperm cells leave the body; it also discharges urine Placenta- network of blood vessels and other tissues by which the unborn child is attached to the wall of the uterus.grows out of the endometrium The umbilical cord is attached to it. It is the interface between mother and developing fetus. Pregnancy-the process in a woman from conception to birth Pregnant-the condition of a woman with an embryo or fetus in her uterus Progesterone pregnancy hormone, which is first produced by the corpus luteum and then by the placenta. * increases lining of endometrium. *maintains pregnancy *helps develop mammary glands. Prostate gland- surrounds the upper end of male urethra and produces part of the fluid that mixes with the sperm to form semen. Prostate fluid alkaline helps to protect sperm from vaginal acids. Scrotum- pouch of loose skin containing the testes.houses and air-conditions the testicles by moving and sweating. Semen-the mixture of sperm and fluids released during ejaculation. Semen comprised of sperm, fructose, prostate fluid and oil from Cowper s gland. Seminal vesicles-small saclike organs opening into each vas deferens near the upper end of the urethra; produce part of the fluid that mixes with the sperm to form semen; provide food (fructose) for the sperm. Seminiferous tubules - tubes in testes that produce sperm Sexual intercourse- entry of penis into vagina and subsequent release of semen; also called coitus Sperm-the male sex cell (male gamete or spermatozoon), which contains 23 chromosomes in human. Spermatozoon-scientific name for sperm Spontaneous abortion--synonym for miscarriage Testes- male sex glands; produce sperm cells and testosterone; Testicles-synonym for testes Testosterone male hormone that regulates development of penis, muscles, body hair, change of voice. Umbilical cord- ropelike structure connecting embryo or fetus to placenta within the uterus. Urethra-the tube through which urine is expelled from the bladder in both males and females and through which semen leaves the male body Uterus = womb - the hollow pear-shaped organ in which a baby develops before it is born; Vagina- passage from the uterus to the outside of the body, accepts the penis during intercourse. It is the birth canal & menstrual fluids leave through it Vas deferens- tube extending from each epididymis to the urethra in males Womb-synonym for uterus Yolk sac-a structure that develops for the nutrition of embryo during early embryonic life and then ceases to function Zygote - The cell formed by the union of two gametes. [ fertilized ovum before cleavage.] 36

38 IMPORTANT NOTES An adult male produces over to sperms each day. Human female oogonial development by mitosis is completed by 25 weeks of foetus and no oogonia are formed after birth. Sperm entry into the ovum stimulates MPF (M phase promoting factor) & APC ( Anaphase promoting complex) for completion of Meiosis II. During Spermatogenesis, spermatogonium produces four sperms while in oogenesis, oogonium produces one ovum and two polar bodies. Human Sperm contains Clupein proteins. Yolk nucleus: A mass of mitochondria and golgi bodies near nucleus is called as yolk nucleus and controls vitellogenesis. Maximum level of estrogen 12 th day, LH-13th day, Progestrone 21st day, Corpous luteum formation 19 th day of menstrual cycle. Menstrual cycle is absent during pregnancy, lactation periods and permanently during menopose. Two ovaries alternate in ovulation. 13 mature eggs are released per year, so about 416 eggs (13x32 years) are ovulated during whole reproductive period of human female. Menstruation is also called Weeping of uterus for the lost ovum or Funeral of unfertilized eggs. In human embryo, yolk sac degenerates since eggs is microlecithal, which shows evolutionary significance. Placenta acts as a physiological barriers and an ultra-filter between foetal and maternal blood. Progesterone is also called pregnancy hormone since its secretions controls pregnancy. Teratogens are physical, chemical, biological agents which may cause malformation in developing embryo. Period between fertilization and parturition is called gestation periods. Varies between 266 days up to 280 days ( 49 weeks) 1) Zygote undergoes mitosis to form 16 celled embryo. What is the stage known as? (1) Hint-Blastomeres. 2)Name the important mammary gland secretions that help in resistance of the new born baby. 1) Hint- Colostrum 3) Fill in the boxes Spermatogenesis Secondary spermatocytes Spermatozoa 4) Why does fertilization take place in fallopian tube and not in the uterus.(2) Hint-ovum and sperms must be transported to the ampullary isthmic region simultaneously for fertilization. 5) Which cell organelle is present in the neck of the sperm? What is its significance? ( 2) Hint-Acrosome, enzymes. Chapter-4: REPRODUCTIVE HEALTH 37

39 Reproductive Health: Acc. to WHO, reproductive health means a total well being in all aspects of reproduction, i.e. physical, emotional, behavioural and social. India was the first countries in the world to initiate family planning programmes in Objective of Reproductive and Child Health Care (RCH) programmes : Creating awareness about reproduction related aspects Awareness created with the help of audio-visual and the print-media governmental and non-governmental agencies. Introduction of sex education in schools to provide right information to the young so as to discourage children from believing in myths and having misconceptions about sex-related aspects. Proper information about reproductive organs, adolescence and related changes, safe and hygienic sexual practices, sexually transmitted diseases (STD), AIDS, etc., Educating people, especially fertile couples and those in marriageable age group, about -available birth control options, - care of pregnant mothers, -post-natal care of the mother and child, -importance of breast feeding, -equal opportunities for the male and the female child, etc., Awareness of problems - due to uncontrolled population growth, - social evils like sex-abuse and sex-related crimes, etc., Require strong infrastructural facilities, professional expertise and material support. provide medical assistance and care to people in reproduction-related problems like pregnancy, delivery, STDs, abortions, contraception, menstrual problems, infertility, etc. Implementation of better techniques and new strategies. Amniocentesis : a statutory ban on (a foetal sex determination test based on the chromosomal pattern in the amniotic fluid surrounding the developing embryo) for sex-determination to legally check increasing female foeticides, massive child immunisation, etc., are some programmes that merit mention in this connection. POPULATION EXPLOSION AND BIRTH CONTROL The world population which was around 2 billion (2000 million) in 1900 rocketed to about 6 billions by A rapid decline in death rate, maternal mortality rate (MMR) and infant mortality rate(imr) due to RCH. Advertisement showing a happy couple with two children with a slogan Hum Do Hamare Do. Statutory raising of marriageable age of the female to 18 years and that of males to 21 years. Methods of birth control Natural Method: Coitus Interruptus: Coitus interruptus means 'interrupted sex" (penis is withdrawn from the vagina just before ejaculation). Advantage - method does not require the use of any drug, does not interfere with normal body functions. The failure rate is high at 15-18%. Periodic Abstinence: couples avoid or abstain from coitus from day 10 to 17 of the menstrual cycle when ovulation could be expected. Lactational Amenorrhea : (absence of menstruation) During intense lactation, chance of conception are almost nil but effective upto 6 month after parturition. 38

40 Barrier methods: In barrier methods of birth control, a barrier is placed between the penis and the vagina during intercourse so that the sperm cannot meet the ovum for fertilization. Male Condoms:, usually made of latex that covers the erect penis during penetration of the vagina. Female Condoms: made of polyurethrane, loose sheath with two rings on either side. can be inserted about 8 hours prior to sexual intercourse and can be kept in for about another 12 hours after intercourse. Can be used more than once during this period. Condoms protect against pregnancy as well as sexually transmitted diseases (STDs), including HIV/AIDS. Diaphragm: vaginal - a small saucer shaped rubber sheath with a metal coil in its rim which is fitted across the mouth of the uterus (cervix). Cervical Cap: The cervical cap is a small dome-shaped rubber device fitted on the cervix. It is uncomfortable to apply and is rarely used nowadays. Vaginal Sponge: Small polyurethrane round device which needs to be placed inside the vagina before sexual intercourse. It releases spermicide which makes sperm inactive. It should be left in place for 8 hours after use and can be used more than once during this time. The sponge also acts as a barrier contraceptive to some extent since it swells up to fit across the cervix once it is inside the vagina. Spermicidal creams, jellies and foams are usually used alongwith these barriers. Hormonal Methods: Drugs are used to either prevent ovulation or to prevent implantation of the embryo after fertilization. Combined oral contraceptives contains two hormones similar to the natural hormones in a woman s body---an progestogens or progestogen-estrogen combination used by females. Oral Contraceptive pills: They are based on hormones results to prevent ovulation & also to disrupt the normal growth of the internal uterine lining (endometrium), Centchroman: This is a non-hormonal non steroidal contraceptive. The main function is to cause a slowing down in the growth rate of the internal uterine lining as well as to speed up the movement of the embryo so that implantation cannot occur. It is a once a week pill. Eg-Saheli. Subdermal Implants Capsules placed under the skin of a woman s upper arm. The capsules supply a steady, very low dose. Norplant implants contain no estrogen. Norplant capsules thicken cervical mucus making it difficult for sperm to pass through. It stops ovulation (release of eggs from ovaries) in about half of the menstrual cycles after the first year of use. Emergency Oral Contraception After unprotected sex, emergency oral contraception can prevent pregnancy. Sometimes called postcoital or morning after contraception. Mainly stops ovulation. Regular use of emergency contraceptives has serious health hazards. Intra-Uterine Devices (IUDs): IUDs are contraceptive devices which are placed inside the uterus. Small, flexible plastic frame. Has copper wire or copper sleeves on it. Inserted into a woman s uterus through her vagina. Preventing sperm and egg from meeting. Perhaps the IUD makes it hard for sperm to move through the woman s reproductive tract, and it reduces the ability of sperm to fertilize the egg. Prevent the egg from implanting itself in the wall of the uterus. 39

41 IUCDs prevent pregnancy by making the endometrium unreceptive to the fertilized ovum. Stimulates the endometrium to release leukocytes (WBCs) and prostaglandins making it hostile to the sperm.causes bizarre and irregular growth of the endometrium. Prevents implantation of a fertilized ovum. IUDs like Copper-T s also come wrapped in copper. Copper is toxic to sperms and is a method of enhancing the contraceptive effect of the IUDs. The IUCDs can come in various shapes and sizes. Lippes Loop: The Lippes loop consists of a thin plastic (or polyethylene)wire bent in a series of S- shapes. Lippes loop Multiload 375 Copper-Ts l Copper T: T-shaped structure which stays inside the uterus with the long arm of the T along the uterine cavity (endometrium) and the shorter arms transversely across the upper part of the endometrium. Surgical Methods: These are more or less permanent methods of contraception. Tubectomy : Both the female tubes are tied off and usually cut during tubal ligation to prevent the sperm from reaching the ovum during intercourse. Vasectomy:The two tubes which carry sperm from the testes to the penis are the vas deferens. Tying them off and cut. 40

42 MEDICAL TERMINATION OF PREGNANCY (MTP) Intentional or voluntary termination of pregnancy before full term is called medical termination of pregnancy(mtp) or induced abortion. MTP has a significant role in decreasing the population though it is not meant for that purpose. Government of India legalised MTP in 1971 with some strict conditions to avoid its misuse. MTPs are considered relatively safe during the first trimester, i.e., upto 12 weeks of pregnancy. Second trimester abortions are much more riskier. SEXUALLY TRANSMITTED DISEASES (STDS) Diseases or infections which are transmitted through sexual intercourse are collectively called sexually transmitted diseases (STD) or venereal diseases (VD) or reproductive tract infections (RTI). SL. NO. STD CAUSAL AGENT 1 CHLAMYDIOSIS Chlamydia trachomatis 2 GONORRHOEA Nisseria gonorrhea 3 TRICHOMONIASIS Tricomonas vaginalis 4 GENITAL HERPES Herpes simplex virus 5 SYPHILIS Trepanema pallidum 6 GENITAL WART Human papilloma virus 7 HEPATITIS-B Hepatitis B virus SYMPTOMS Painful urination & intercourse Mucus discharge from penis/vagina Painful urination in men Inflammation, Itching& vaginal white discharge (Leucorrhoea) Genital sores, Fever Initially sores in genitalia & mouth, Rashes EFFECT ON FOETUS Premature birth,blindness, Pneumonia Still birth, Blindness Not known Still birth, Brain damage Premature birth, Miscarriage, Still birth EFFECT ON PERSON AFFECTED Pelvic inflammatory disease, Infertility, Ectopic pregnancy Pelvic inflammatory disease, Infertility, Rash, Death Valvar erythema, Burning dysuria Cervical cancer. Death Warts on genitalia Not known Cervical cancer Fatigue, Fever, Jaundice, Rash, Abdominal pain 8 AIDS HIV Fever, Prone to infection, Inflammation Low birth weight AIDS affected Liver cirrhosis, Liver cancer Dementia, Death One could be free of these infections by following the simple principles given below: (i) Avoid sex with unknown partners/multiple partners. (ii) Always use condoms during coitus. 41

43 (iii) In case of doubt, one should go to a qualified doctor for early detection and get complete treatment if diagnosed with disease. INFERTILITY Unable to produce children inspite of unprotected sexual co-habitation. Infertility when a couple fails to conceive after one year of sexual life without contraception. Infertile couples could be assisted to have children through certain special techniques commonly known as Assisted Reproductive Technologies (ART). InVitro Fertilisation (IVF) : fertilization outside the body under controlled conditions. IVF fertilisation outside the body in almost similar conditions as that in the body) followed by embryo transfer (ET) upto 8 celled blastomeres. This technique also called test tube baby programme. Zygote Intra Fallopian Transfer (ZIFT) : The zygote or early embryos (with upto 8 blastomeres) could then be transferred into the fallopian tube is called ZIFT. Intra Uterine Transfer (IUT) : Transfer of embryo with more than 8 blastomeres to 32 cells, into the uterus is called IUT. Embryos formed by in-vivo fertilization (fusion of gametes within the female) also could be used for such transfer to assist those females who cannot conceive. Gamete Intra Fallopian Transfer (GIFT) : Transfer of an ovum collected from a donor into the fallopian tube of another female who cannot produce one, but can provide suitable environment for fertilisation and further development. Intra Cytoplasmic Sperm Injection(ICSI) : It is another specialised procedure to form an embryo in the laboratory in which a sperm is directly injected into the ovum. Artificial Insemination (AI) Technique : In this technique the semen collected either from the husband or a healthy donor is artificially introduced either into the vagina or into the uterus (IUI intra-uterine insemination) of the female. Questions. Q1) Table of certain terms associated with ART. Fill in the spaces a,b,c,d.(1x4 ) IVF&ET A b Introduction of zygote/embryo with 8 blastomeres into fallopian tube. c Introduction of ova of a donor into the fallopian tube d Introduction of semen from the husband or healthy donor into the uterus. Ans.( a) test tube baby programme.( b) ZIFT (zygote intra fallopian transfer ).( c) GIFT (gamete intra fallopian transfer ) (d ) IUI (intra uterine insemination ) Q2) Name 3 incurable sexually transmitted diseases and their causative organisms ( 3) 1. Hepatitis-B Hepatitis-B virus 2.Genital herpes herpes simplex virus 3. AIDS HIV (Human Immunodeficiency virus) Q3)Why is the term test tube baby a misnomer.(3) Baby not developed in test tube. Only fertilization carried out in test tube in lab conditions. The fertile egg is then transferred into the fallopian tube or uterus where it develops and grows into a normal baby is born. Q4. Why do intensely lactating mothers do not generally conceive? Due to suppression of gonadotropins Chapter 5 : PRINCIPLES OF INHERITANCES AND VARIATION 42

44 Genetics : branch of science which deals the study of inheritances and variations of characters. Know the terms Terms Locus Gene Allele Homozygous Heterozygous Homozygous Dominant Homozygous recessive Genotype Phenotype Punnet Square Meaning Address/ location of a gene in a chromosome e.g. T,A.b,d Structural & functional unit of chromosome. Allelomorphs= alternative form of a gene e.g. T and t OR A and a Both alleles of a gene at a locus similar e.g. AA or aa Both alleles of a gene at a locus dissimilar e.g. Aa or Tt Both alleles of a gene at a locus similar & dominant e.g. AA Both alleles of a gene at a locus similar & recessive e.g. aa Genetic constituent of an organism Physical appearance Graphical representation to calculate the probability of all possible genotype. MENDEL S LAW OF INHERITANCE Salient features of Mendel s Experiment : Mendel s investigations into inheritance patterns it was for the first time that statistical analysis and mathematical logic were applied to problems in biology. Mendel selected two opposing traits, e.g., tall or dwarf plants, yellow or green seeds. This allowed him to set up a basic framework of rules governing inheritance. Mendel selected 14 true-breeding pea plant varieties. 43

45 His experiment had a large sampling size; it gives credibility to his data. Why Mendel select pea plant? He selected pea plant for following reasons : Pea is a self pollinated plant & cross pollination is also possible. Many varieties were available with observable alternate forms for a trait. Short life span. Can be easily grown in small place. Seeds easy to handle. CONTRASTING CHARACTERS Mendel's first law ( Law of dominance ) : (i) Characters are controlled by discrete units called factors (genes). (ii) Factors occur in pairs. (iii) In a dissimilar pair of factors one member of the pair dominates (dominant) the other (recessive). The law of dominance is used to explain the expression of only one of the parental characters in a monohybrid cross in the F 1and the expression of both in the F2. It also explains the proportion of 3:1 obtained at the F2. (Refer Fig page 73, NCERT) Mendel's Law of segregation (Purity of Gametes): The two alleles received, one from each parent, segregate independently in gamete formation, so that each gamete receives one or the other with equal probability. (Can be explained by monohybrid cross). Mendel's law of Independent Assortment : Two characters determined by two unlinked genes are recombined at random in gamete formation, so that they segregate independently of each other, each according to the first law (note that recombination here is not used to mean crossing-over in meiosis). (Can be explained by dihybrid cross) (Refer Fig page 79, NCERT) Test Cross and Back Cross : Test cross is a back cross but back cross is not a test cross. In a test cross, hybrid cross with homozygous recessive individuals. In a back cross, hybrid cross with homozygous recessive & homozygous dominant individuals. Significance : Both are used to determine the frequency of gene or allele. It is used in horticulture, animal breeding and in production of gene knockout organisms. Incomplete Dominance : Dominant gene is not fully expressed on recessive gene. So, the phenotype of hybrid do not resemble with any of the parents. Eg- Antirrhinum majus (snapdragon), Mirabilis jalapa (4 O clock plant). 44

46 Genotype & phenotype ratio : 1:2:1 (Refer Fig page 76, NCERT). Co-dominance : Both parental genes expressed in F1 progeny so the offspring shows resemblance with both the parents. Eg- ABO blood group types in human. Blood group shows 3 different alleles (I A, I B, I O ) and 6 different possible genotypes. Cross between I A I O x I B I O, shows the law of dominance, co-dominance & multiple alleles. POSSIBLE BLOOD GROUP OF PROGENY WITH RESPECT TO THE BLOOD GROUP OF PARENTS Parent Progeny A B AB O A X A A X O A X B B X B B X O AB X A AB X B AB X O AB X AB O X O KEY + = POSSIBLE - = NOT POSSIBLE (Refer Table page 77, NCERT). POLYGENIC INHERITANCE : Galton in 1883 suggested that many instances of continuous variation are heritable like height, mental capabilities. The character is determined by more than one gene each with the same but cumulative phenotypic effect. Quantitative characters like plant height, yield of crops (size, shape and number of seeds and fruits per plant), intelligence in human beings and milk yield in animals determined by many genes in cumulative. Skin colour determine by 3 genes ( 6 allels) (i) Few individuals fall into parental categories; (ii) The expression level of the phenotype is dependent upon the number of contributive alleles and is hence more quantitative. Polygenic inheritance also shows by kernel colour in wheat and inheritance of cob length in maize. It is generally believed that during evolution there was duplication of chromosome or chromosome parts thereby leading to multiple copies of the same gene. A large number of characters are controlled by polygenes in which alleles contribute additively to a phenotype. This results in polygenic inheritance. 45

47 Pleiotropy : single gene may produce more than one effect. The basis of Pleiotropy is the interrelationship between the metabolic pathways that may contribute towards different phenotypes. Eg. Phenylketonuria, eye mutation in Drosophila and starch synthesis & size of starch grain. Basic outline of Mendels cross 1. Pure breeding parents for a pair of contrasting character (allelic pair) is taken Eg.Tall pure-bred pea plants (TT) & short pure-bred pea plants (tt) 2. Gamete formation (Meiosis) 3. Hybridization (crossing is done) 4. F1 generation - the product of the above cross (are called hybrids) 5. Selfing (allowed to self fertilize / self breeding) 6. Gamete formation (Meiosis) 7. F2 generation - the product of the above selfing 8. Analysis of result (Phenotype and Genotype) Chromosomal theory of Inheritance : It is proposed by Water Sutton and Theodore Boveri in They found the behavior of chromosomes was parallal to the behavior of factor (genes) and used chromosome movement to explain Mendel s law. Gene and chromosomes shows similar behavior as followings- Occur in pairs Segregate at the time of gamete formation such that only one of each pair is transmitted to a gamete Independent pairs segregate independently of each other. (Refer Fig. 5.9, page 82 NCERT). Linkage: According to Morgan, physical association or linkage of two genes is called linkage. The new combination are produced because homologous chromosomes can exchange segments when they are paired. This process (crossing over) results in recombination of alleles between the homologous chromosomes. The probability of recombination between any two genes serve as a measure of genetic distance between the genes and allowed the construction of genetic map. (A) Two alleles and their linked genes have switched locations via recombination. Recombined haploid chromosomes segregate separately during meiosis as gametes before fertilization. (B) Sample recombination frequencies between genes demonstrating higher rates of recombination for genes further apart. Sex determination : x body was discovered by Henking in Sex chromosome : the chromosomes determine the sex of living. Autosomal chromosomes : they determine the characters other than sex of living. 46

48 Name of Living Male Female Human XY XX Drosophila XY XX Insect XO XX Bird ZZ ZW Honey Bee X M (Drone), X M X M (Male) XX Male Heterogamety : Male produced two type of gametes. Eg. Human, Drosophila. Female heterogamety : female produced two type of gametes. Eg.Birds. Mutation : Sudden changes in DNA. Mutagens : Chemicals/agents that caused mutation. Type of gene mutation Reason Point mutation Change in single base eg sickle-cell anaemia Frameshift mutation Deletion/insertion/duplication/addition of one or two bases Type of Reason chromosomal mutation Structural aberration Loss or gain of large segment of DNA Numerical variations Aneuploidy Addition/ deletion one or more chromosomes Polyploidy Addition/ deletion one or set chromosomes Trisomy 2n+1 monosomy 2n- 1 3n, 4n etc. Pedigree Analysis Pedigree is a chart of graphic representation of record of inheritance of a trait through several generations in a family Symbols used:- refer NCERT Text Book GENETIC DISORDER Chromosomal Disorder Mendelian Disorder These are due to absence or excess of abnormal These are due to alteration or mutation of one arrangement of one or more chromosomes. gene. Eg. Down, Klinefelter s, Turner s syndrome. Eg. Sickle cell anaemia, haemophilia, thalassaemia Mendelian Disorder Disorder Reason Symptoms Haemophilia Sex linked recessive disease (X). Females are unaffected carrier. Non stop bleeding, no blood clotting. Sickle Cell Anaemia Autosomal recessive trait on chromosome 11. Sickle shape RBC due to replace the glutamic acid by valine. Oxygen carry capacity reduced. Phenylketonuria Autosomal recessive trait on chromosome 12. Mutation in phenyl alanine hydroxylase enzyme Mental retardation, presence of phenyl pyruvate in urine. results in accumulation of phenyl pyruvate. Colour Blindness Sex linked recessive disorder (X). Unable to differentiate green and red colour 47

49 Thalassaemia : it is caused by deletion (mutation) in globin chain of haemoglobin. It reduced or absence the synthesis of globin in excess of others. Excess globins are insoluble & accumulate in RBC, it precipitate and lysis the RBC, cause anaemia. Alpha thalassaemia : Involve two gene HBA1 & HBA2 (4 loci) located on 16 th chromosomes. Due to deletion, decrease the synthesis of alpha globin & enhance beta globin. Excess beta globin in adult & new born babies, unstable the tetramer of globin results in abnormal oxygen carring capacity. Beta thalassaemia : Involve one gene HBB on chromosome 11. Due to deletion, increase the synthesis of alpha globin & decrease the beta globin. Excess alpha globin bind to RBC membrane & damage them results in anaemia. CHROMOSOMAL DISORDER Name of Disorder Reason Symptoms Down s Syndrome Trisomy of 21 Chromosome Short statured with small round head, furrowed tongue & partially open mouth, flat back, broad flat face, slanting eyes, broad palms with palm crease, many loops on finger, congenital heart disease, Klinefelter s Syndrome physical, psychomotor & mental retardation. 47 (XXY) In male (XXY): tall stature, feminine physique, breast development (gynaecomastia), female type pubic hair pattern & poor beard development and sterile. Turner s Syndrome 45 (XO) Short stature, rudimentary ovaries (sterile), breast poor developed, lack of secondary sexual characters. Now try to answer 1. Is it possible that this pedigree is for an autosomal dominant trait? 2. Can two individuals that have an autosomal dominant trait have unaffected children? 3. Is it possible that this pedigree is for an autosomal dominant trait? 4. Is it possible that this pedigree is for an autosomal dominant trait? 5. Is it possible that the pedigree above is for an autosomal recessive trait? 6. Assuming that the trait is recessive, write the genotype of each individual next to the symbol A = normal a = the trait (a genetic disease or abnormality) 7. Is it possible that the pedigree above is for an autosomal recessive trait? 8. Write the genotype of each individual next to the symbol 48

50 9. Is it possible that the pedigree above is for an autosomal recessive trait? 10. Is it possible that the pedigree above is for an X-linked recessive trait? 11. Write the genotype next to the symbol for each person in the pedigree 12. Is it possible that the pedigree above is for an X-linked recessive trait? 13. Is it possible that the pedigree above is for an X-linked recessive trait? 14. Is it possible that the pedigree above is for an X-linked recessive trait? 15. Is it possible that the pedigree above is for an X-linked recessive trait? 16. Is it possible that the pedigree above is for an X-linked recessive trait? Clues Affected Unaffected Autosomal Dominant AA aa Aa Autosomal Recessive aa AA Aa X- chromosome linked recessive X X X Y XX X X XY Questions 1 Mark Questions Q1. Mendel s work was rediscovered by three scientists independently. Name any two of them. Q2. How do we predict the frequency of crossing over between any two linked genes? Q3. Why did Mendel select pea plant for his experiment? Q4. In a monohybrid cross the genotypic and phenotypic ratio is 1:2:1. What type of Inheritance is it example of? Give one example. Q5. If a human zygote has XXY sex chromosomes along with 22 pairs of autosomes. What sex will the individual be? Name the syndrome. Q6. Which of the following is a dominant & recessive trait in garden peatall stem, constricted pod. 2 Mark Questions Q7. A mother with blood group B has a fetus with blood group A father is A. Explain the situations? Q8. The genes for hemophilia are located on sex chromosome of humans. It is normally impossible for a hemophilic father to pass the gene to his son. Why? Q9. Justify the situation that in human beings sex of the child is determined by father and not by mother? Q10. What is trisomy? Give one example. 11)Differentiate between Genotype and Phenotype ( 2) 49

51 Genotype 1 Total genetic constitution of an Individual 2 Individuals with different genotype may produce the same phenotype. Phenotype External appearance of an individual. Individuals with different phenotypes always have different genotypes. 12)Distinguish between Complete and Incomplete linkage. (2) Complete Linkage Incomplete linkage 1 No crossing over between the genes Crossing over at the time of gamete formation 2 Linked genes show no recombination Recombination Progeny is produced in addition to parental type. 3 Marks Questions Q13. A man with AB blood group marries a woman with AB blood group. (i) Work out all possible genotypes & phenotypes of the progeny. (ii) Discuss the kind of domination in the parents & progeny. Domination in Father Co dominance Domination in progeny - Dominance Q14. Enumerate points to establish parallelism between chromosomes & genes. Ans14. Refer Pg 82 NCERT Book Q15. What is Pedigree Analysis? What are the symbols generally used in it? Ans15. Refer Pg87,88 of NCERT Book 5 Marks Questions Q16. A dihybrid heterozygous round, yellow seeded garden pea was crossed with a double recessive plant. (i) What type of cross is this? (ii) Work out the genotype & phenotype of the progeny. (iii) What principle of Mendel is illustrated by it? Ans16. Test Cross (1) Working out (3) Principle of segregation (1) Q17. Describe the nature of inheritance of the ABO blood group in humans. In which ways does this inheritance differ from that of height of the plant in garden pea? Ans17. Refer Pg 77 NCERT Book (3) Dominance & multiple allelism where as height shows dominance (2) 50

52 Chapter 6. MOLECULAR BASIS OF INHERITANCE DNA largest macromolecule made of helically twisted, two, antiparallel polydeoxyribonucleotide chains held together by hydrogen bonds. X-ray diffraction pattern of DNA by Rosalind Franklin showed DNA a helix. Components of DNA are (i) deoxyribose sugar, (ii) a phosphate, and (iii) nitrogen containing organic bases. DNA contains four different bases called adenine (A), guanine (G) cytosine (C), and thymine (T). These are grouped into two classes on the basis of their chemical structure: (i) Purines (with a double ring structure) and (ii) Pyrimidines (with a single ring structure) 1953.James Watson and Francis Crick proposed three dimensional structure of DNA and won the Nobel prize. DNA double helix with sugar phosphate back bone on outside and paired bases inside. Planes of the bases perpendicular to helix axis. Each turn has ten base pairs.( 34 A 0 ) Diameter of helix 20 A 0. Two strands of DNA antiparallel. DNA found both in nucleus and cytoplasm. Extranuclear DNA found in mitochondria and chloroplasts. Two chains complementary Two chains held together by hydrogen bond. Adenine-Thymine pair has two hydrogen bonds. Guanine-Cytosine pair has three hydrogen bonds. Upon heating at temperature above degree two strands uncoil and separate (Denaturation) On cooling two strands join together (renaturation /annealing) DNA is mostly right handed and B form. Bacterial nucleoid consists of a single circular DNA molecule. 51

53 PACKAGING OF DNA HELIX DNA of eukaryotes is wrapped around positively charged histone proteins to form nucleosome. Nucleosome contains 200 base pairs of DNA helix. Histone octamer =2(H2a+H2b+H3+H4) Linker DNA bears H1 protein Chromatin fibres formed by repeated units of nucleosomes. Non histone proteins required for packaging. Regions of chromatin, loosely packed and stains lightly called euchromatin. Regions of chromatin, densely packed and stains darkly is called heterochromatin. NUCLEOSOME DNA AS THE GENETIC MATERIAL Transformation experiment or Griffith effect. Griffith performed his experiments on Mice using Diplococcus pneumoniae. Two strains of bacteria are S-type and R-type cells. Experiments Living S-strain Injected into mice Mice killed Living R-strain Injected into mice Mice lived Heat Killed S-strain Injected into mice Mice lived Living R-strain + Heat Killed S-strain Injected into mice Mice killed # Griffith concluded that R type bacteria is transformed into virulent form. # Transformation - change in the genetic constitution of an organism by picking up genes present in the remains of its relatives. BIOCHEMICAL CHARACTERISATION OF TRANSFORMING PRINCIPLE # Proved by Oswarld Avery, Colin Macleod, Maclyn Mc Carty : they use protein-digesting enzymes (proteases) and RNA-digesting enzymes (RNases) did not affect transformation, so the transforming substance was not a protein or RNA. Digestion with DNase did inhibit transformation, suggesting that the DNA caused the transformation. 52

54 From this we conclude that DNA is the genetic material. HERSHAY & CHASE EXPERIMENT : DNA is a genetic material in viruses (bacteriophage) was discovered by Alfred Hershey and Martha Chase (1952). They grew some viruses on a medium that contained radioactive phosphorus and some others on medium that contained radioactive sulfur. Viruses grown in the presence of radioactive phosphorus contained radioactive DNA but not radioactive protein because DNA contains phosphorus but protein does not. Similarly, viruses grown on radioactive sulfur contained radioactive protein but not radioactive DNA because DNA does not contain sulfur. Bacteria which was infected with viruses that had radioactive DNA were radioactive, indicating that DNA was the material that passed from the virus to the bacteria. Bacteria that were infected with viruses that had radioactive proteins were not radioactive. This indicates that proteins did not enter the bacteria from the viruses. DNA is therefore the genetic material that is passed from virus to bacteria Hershay & Chase Experiment Semi conservative nature of DNA Mathew Messelson and Franklin Stahl s. E.coli Grown on 15 NH 4 Cl culture medium 53

55 Both strands of DNA have 15 N (N Shifted to 14 NH 4 Cl culture medium DNA extracted subjected to CSCl density gradient centrifugations After 20 min. After 40 min. Hybrid/ Intermediate type of DNA (N 15 N 14 ) Equal amount of light DNA (N 15 N 14 ) and hybrid DNA (N 15 N 14 ) 8. 3 Replication of DNA In Eukaryotes: Definition: "Process by which DNA produces daughter DNA molecules which are exact copies of the original DNA." In eukaryotes, DNA is double stranded. The two strands are complementary to each other because of their base sequences. Semi-conservative method of DNA replication Important points: (i) Most common method of DNA replication. (ii) Takes place in the nucleus where the DNA is present in the chromosomes. (iii) Replication takes place in the S-phase (synthesis phase) of the interphase nucleus. (iv) Deoxyribose nucleotides needed for formation of new DNA strands are present in nucleoplasm. At the time of replication, the two strands of DNA first separate. Each strand then acts as a template for the formation of a new strand. A new strand is constructed on each old strand, and two exactly identical double stranded DNA molecules are formed. In each new DNA molecule, one strand is old (original) while the other is newly formed. Hence, Watson and Crick described this method as semi-conservative replication. (A) An overall process of DNA replication showing replication fork and formation of new strands template and lagging template. The various steps involved in this process are summarized as follows: 54

56 i. Mechanism of replication starts at a specific point of the DNA molecule, called origin. ii. At origin, DNA strand breaks because of an incision (nick). This is made by an enzyme called incision enzyme (endonuclease). iii. The hydrogen bonds joining the two strands are broken by the enzyme. iv. The two strands start unwinding. This takes place with the help of a DNA unwinding enzyme Helicases. Two polynucleotide strands are thus separated. v. The point where the two strands separate appears like a fork or a Y-shape. This is described as a replicating fork. vi. A new strand is constructed on each old strand. This takes place with the help of a small RNA primer molecule which is complimentary to the DNA at that point. vii. Each old DNA strand acts as a template (site) for the construction of new strand. The RNA primer attaches itself to the old strand and attracts the enzymes (DNA polymerase III) which add new nucleotides through base complementation. The deoxyribose nucleotides are present in the surrounding nucleoplasm. New DNA strand is thus constructed opposite to each old strand. viii. Formation of new complementary strand always begins at the 3' end of the template strand (original strand) and progresses towards the 5' end (ie in 3' - 5' direction). Since the new strand is antiparallel to the template strand, it is obvious that the new strand itself is always developed in the, 5'-3' direction. For this reason when the two original strands separate (then with respect to the origin of separation), one acts as 3'-5' template while the other acts as 5'- 3' template. ix. Of the two, the replication of 3'-5' template begins first. Hence the new strand formed on it is called the leading strand. The other template (5'-3') must begin replication at the fork and progress back toward the previously transcribed fragment. The new strand formed on it is called the lagging strand. x. Replication of the lagging strand takes place in small fragments called Okazaki fragments. These are then connected together by the enzyme ligase. xi. Replication may take place in only one direction on the DNA helix (unidirectional) or in two directions (bidirectional). xii. At the end of the process, two double stranded DNA molecules are formed from the original DNA molecule. Three major types of RNA: 1. Messenger RNA or mrna- has the information to make a protein. It is very unstable and comprises ~5% of total RNA polymer. Its length is highly variable, of the range nucleotides. 2. Transfer RNA or trna- small molecule, about 90 nucleotides long. It is highly folded into an elaborate 3- d structure and comprises about 15% of total RNA. 55

57 3. Ribosomal RNA or rrna- 80% of the total RNA, is associated with subcellular structures called ribosomes in which the polymer length varies from nucleotides and is folded into an elaborate structure which give ribosomes their shape. Transcription in Prokaryotes The mrna provides the template, trna brings amino acids and reads the genetic code, and rrnas play structural and catalytic role during translation. There is single DNA-dependent RNA polymerase that catalyses transcription of all types of RNA in bacteria. RNA polymerase binds to promoter and initiates transcription (Initiation). It uses nucleoside triphosphates as substrate and polymerises in a template depended fashion following the rule of complementarity. It somehow also facilitates opening of the helix and continues elongation. Only a short stretch of RNA remains bound to the enzyme. Once the polymerases reaches the terminator region, the nascent RNA falls off, so also the RNA polymerase. This results in termination of transcription. initiation-factor(σ) termination-factor(ρ) to initiate and terminate the transcription. Transcription in Eukaryotes RMT(Radhey Mohan tiwary) RNA Pol I Ribosomal RNA RNA Pol II-Messanger RNA RNA Pol III- Transfer RNA Splicing : removal of introns Capping : attachment of 5 methyl guanosine at 5 I Tailing : Attachment of poly A (polyadenylation) 56

58 GENETIC CODE Universal commaless Initiation Codon AUG Triplet Non ambigious Genetic Code Linear Degenerate Non Nonsense codon (UAA,UAG,UGA) overlapping The salient features of genetic code are as follows: (i) The codon is triplet. 61 codons code for amino acids and 3 codons do not code for any amino acids, hence they function as stop codons. (ii) One codon codes for only one amino acid, hence, it is unambiguous and specific. (iii) Some amino acids are coded by more than one codon, hence the code is degenerate. (iv) The codon is read in mrna in a contiguous fashion. There are no punctuations. (v) The code is nearly universal: for example, from bacteria to human UUU would code for Phenylalanine (phe). Some exceptions to this rule have been found in mitochondrial codons, and in some protozoans. (vi) AUG has dual functions. It codes for Methionine (met), and it also act as initiator codon. TRANSFER RNA (trna) trna has an anticodon loop that has bases complementary to the code, it also has an amino acid acceptor end to which it binds to amino acids. trnas are specific for each amino acid For initiation, there is another specific trna that is referred to as initiator trna. There are no trnas for stop codons. Secondary structure of trna has been depicted that looks like a clover-leaf. In actual structure, the trna is a compact molecule which looks like inverted L. 57

59 Translation:- Process of joining of amino acids by peptide bond to form a polypeptide. 1. Activation of amino acids AA+ATP+E Mg+2 AA-AMP-E+ PPi AA-AMP-E+tRNA AA-tRNA+AMP+E 2. Initiation Small subunit (40s) of ribosome binds with mrna. Charged t RNA specific for initiation codon reaches P site Larger subunit (60s) of ribosome now combines with 40s-m RNA t met Elongation Second t-rna charged with amino acid occupies A site of ribosome. Peptide bond formation between methionine and second amino acids with the help of enzyme peptide transferase. 4. Terminator Translation stops when non sense codons (Stop codons) reached. No t RNA for stop codons (UAA,UAG,UGA) * AA Amino acid *ATP Adenosine Triphosphate *E Pyrophosphate AA AMP-E-Amino acid adenylate enzyme complex AA t RNA Amino acyl-t RNA complex 58

60 LAC OPERON *Discovered by Jacob and Manod., *Experimented on E.coli. The lacoperon consists of one regulatory gene (the igene here the term idoes not refer to inducer, rather it is derived from the word inhibitor). three structural genes (z, y, and a). The i gene codes for the repressor of the lacoperon. The z gene codes for beta-galactosidase (β-gal), which is primarily responsible for the hydrolysis of the disaccharide, lactose into its monomeric units, galactose and glucose. The y gene codes for permease, which increases permeability of the cell to β-galactosides. The a gene encodes a transacetylase and convert active form lactose. Hence, all the three gene products in lac operon are required for metabolism of lactose. Lactose is the substrate for the enzyme beta-galactosidase. It regulates switching on and off of the operon. Hence, it is termed as inducer. Methodologies of Human Genome Project Sequence annotation (Sequence the whole set of genome) 59 Expressed sequence Tags (EST) (Identifying all the genes Expressed as RNA)

61 -Isolation of total DNA from the cell -Fragmentation by restriction endonuclease Fragments cloned in suitable host BAC/YAC Fragments sequenced using automated DNA sequences. Sequences arranged on the basis of overlapping regions. Alignment of the sequences by specialized computer based programmes Functions of 50% discoursed genes unknown millions Nucleotides Average gene consists of 3000 bases Repetitive sequences contribute large portion Largest gene dystrophic Y chromosome has 231 genes Salient features of Human Genome Chromosome-1 has 2968 gene Application of Human genome project -: Identification of defective genes. -: Opportunity to offer early treatment. -: Identification of genes that confer susceptibility to certain disease. -: Prediction of protein that the genes produce. -: Drug designing to enhance or inhibit the activities of the proteins. Total genes 30,000 <2% gene codes protein 60

62 TECHNIQUE FOR DNA FINGER PRINTING Technique developed by Dr.Alec Jeffreys. Process is also known as DNA typing/dna profiling. DNA extraction from the cells in high speed refrigerated centrifuge Amplification of DNA content by PCR (Polymerase chain reactions) DNA fragmentation by Restriction endonuclease Gel electrophoresis Double stranded DNA split into single stranded Southern blotting (Transferring separated DNA to nylon or nitrocellulose sheet) Nylon sheet immerse in a bath having probes/marker* (Hybridisation) Dark band develops at probe site *Probes/ Markers are radioactive synthetic DNA complementary to VNTR QUESTIONS ONE MARK QUESTION Nylon membrane pressed on X-ray film (Autoradiography) 1.Name the genetic material in TMV. 2.Write the scientific name of the plant on which Taylor et al performed their experiment. 3.What would be the proportion of light and hybrid density DNA molecules after 80 minutes of a single cell of E. coli growth? 4.When does DNA replicate in the cell cycle? 5.Name the amino acids having only one codon. TWO MARK QUESTION 1.What is meant by semiconservative nature of DNA replication? 2. What are the functions of DNA polymerase? 3. What is frame shift mutation? Name the type of mutation that does not affect protein synthesis. 4.What are the untranslated regions (UTRs)? 5.Briefly describe polymorphism. 6. What do you mean by phosphodiester bond? Ans: The bond which is formed between the 3 -OH of one deoxyribonucleotide and 5 -phosphate residue of an adjacent deoxyribonucleotide. 7. What type of transcription is found in retrovirus? Name the enzyme. Ans: in retrovirus the genetic information flows from RNA to DNA and is called reverse transcription while the enzyme involved is called reverse transcriptase. 8. What would happen if histones were to be mutated and made rich in amino acids aspartic acid and glutamic acid in place of basic amino acids such as lysine and arginine? 61

63 Ans: If histone proteins were rich in acidic amino acids instead of basic amino acids then they would not have any role in DNA packaging in eukaryotes as DNA is also negatively charged molecule. The packaging of DNA around the nucleosome would not happen. Consequently, the chromatin fibre would not be formed. 9. Explain what happens in frameshift mutation. Name one disease caused by the disorder. Ans: Mutation in which addition/insertion or deletion of one or two bases changes the reading frame from the site of mutation is called frameshift mutation. It may result in polypeptide with different sequences of amino acids. Disease caused by frameshift mutation - sickle-cell anemia. 10. Comment on the utility of variability in number of tandem repeats during DNA fingerprinting. Ans: Tandemness in repeats provides many copies of the sequence for fingerprinting and variability in nitrogen base sequence in them. Being individual-specific, this proves to be useful in the process of DNA fingerprinting. 11. Why is lactose considered an inducer in lac operon? Ans: Lactose binds to repressor molecule and prevents it from binding with the operator, as a result RNA polymerase binds to promoter-operator region to transcribe the structural genes. Thus the lac operon is switched on. 12. If a double-stranded DNA has 20 % of cytosine, calculate the % of adenine in the DNA. Ans: cytosine = 20%, therefore guanine = 20% According to Chargaff s rule, A+T = 100 (G+C) A+T = Since both adenine and thymine are in equal amount. Therefore, Thymine= Adenine = 60%/2 = 30% 13. What is cistron? Ans: Region of the DNA template (gene) coding for a single protein is called cistron. THREE MARK QUESTIONS 1.Describe the discontinuous synthesis of DNA. 2. How is Lac operon switched on in an E.coli cell? 3.Name the three RNA Polymerases found in eukaryotes and mention their functions. 4.Explain the two major approaches involved in the sequencing of genomes. FIVE MARKS QUESTIONS 1.Describe the salient features of the double helical model of DNA. 2. Bring out the salient features of genetic code. 3.Describe in detail the steps in the technique of DNA finger printing. 4.Describe the process of replication of DNA. 5. What is satellite DNA? Name their types. Mention their basis for classification of satellite DNA. 6. What are the differences between DNA and RNA? Ans: DNA 1. Polymer of deoxyribonucleotides consisting of two antiparallel strands. 2. Purine nucleotides are- adenine and guanine. Pyrimidine nucleotides are cytosine and thymine. 3. Main function is to carry all the hereditary characteristics. 4. Mainly present in nuclear material of chromatin fibre, mitochondria and RNA 1. Polymer of ribonucleotides consisting of only a single strand. 2. Purine nucleotides are- adenine and guanine. Pyrimidine nucleotides are cytosine and uracil. 3. Main function is to perform protein synthesis. 4. Mainly present in cytoplasm, nucleolus and chromosome. 62

64 chloroplast. 7. What are B-DNA, A-DNA and Z-DNA? Ans: B-DNA A-DNA Z-DNA 1. In lower concentration of salts or in a partially dehydrated state, this form is present, found in some Gram positive bacteria, right handed double helix. 2. Base pair per turn Diameter 2.6 nm. 1. Most predominant form of DNA, the conformation described by Watson and Crick, present under physiological conditions in the body, right handed double helix. 2. Base pair per turn Diameter 2 nm. 1. It has been discovered in synthetically made oligodeoxynucleotides, left handed double helix. 2. Base pair per turn Diameter 1.8 nm. 8. What do you mean by grooves of DNA? Ans: DNA backbone is somewhat tilted from its vertical axis, it has two uneven grooves or furrowings i.e., one major groove (about 12 A ) and one minor groove (about 6 A ). They are the protein binding sites of DNA. 9. Recall the experiment done by Frederick Griffith. If the RNA, instead of DNA was the genetic material, would the heat killed strain of strain of streptococcus have transformed the r-strain into virulent strain? Explain your answer. Ans: RNA is more labile and prone to degradation (owing to the presence of 2 -OH group in its ribose). Hence heat-killed S-strain may not have retained its ability to transform the R-strain. 10. What do you mean by selfish DNA? Ans: DNA whose role appears to be to mediate its own replicationand survival within the genome, e.g. some satellite DNA, and transposable elements. 11. What are the differences between euchromatin and heterochromatin? Ans: euchromatin Heterochromatin 1. During interphase certain areas in 1. During interphase certain areas in chromatin are loosely coiled and stain chromatin remain tightly coiled or less intensely. condensed and hence stain darkly. 2. These contain the genes or the coding 2. These contain non-coding DNA like the DNA. repetitive DNA. 63

65 CHAPTER-7: EVOLUTION Evolution: Process that results in heritable changes in a population spread over many generations (change in allele frequencies over time) leading to diversity of organisms on earth. It is the genetic change in a population or species over generations (Genes mutate, individuals are selected, and populations evolve). Origin of life : 3.5 bya (billion year ago) Origin of earth : 4.5 bya Origin of universe : 20 bya. Big Bang Theory Single huge explosion expanded universe. The gases condensed under gravitation and formed the galaxies of the present day universe. There was no atmosphere on early earth. Water vapour, methane, carbondioxide and ammonia released from molten mass covered the surface. The UV rays from the sun brokeup water into Hydrogen and Oxygen and the lighter H2 escaped. Oxygen combined with ammonia and methane to form water, CO2 and others. The ozone layer was formed. Theories of origin of Life Theory of Special creation : God or super natural powers created the life. Theory of Panspermia / Cosmozoic : Greek thinkers thought units of life called spores were transferred to different planets including earth. Panspermia is still a favourite idea for some astronomers. Theory of Spontaneous Generation : life has come from decaying matter like straw. o Louis Pasture discarded the spontaneous generation of life by using swan necked flask experiment. Theory of Chemical Evolution : Oparin of Russia and Haldane of England proposed that the first form of life could have come from pre-existing non-living organic molecules (e.g. RNA, protein, etc.) and that formation of life was preceded by chemical evolution. The conditions on earth were high temperature, volcanic storms, reducing atmosphere containing CH4, NH3, etc. Chemical evolution theory was experimentally proved by S.L. Miller & Urey (1953). 64

66 They created electric discharge in a closed flask containing CH4, H2, NH3 and water vapour at C. He observed formation of amino acids. In similar experiments others observed, formation of sugars, nitrogen bases, pigment and fats. These molecules form single cells is called coacervates. The first form of life arose slowly through evolutionary forces from non-living molecules. Evolution of Life forms : A Theory Charles Darwin travelled around the world by a sea voyage in a sail ship called H.M.S. Beagle. He observed the gradual evolution of life forms in Galapagos Island and Malay Archipelago. All the existing life forms share similarities and share common ancestors present at different periods in the history of earth (epochs, periods and eras). Evidences for Evolution : Palaeontological evidences : fossils founds in rock and support the evolution. Different-aged rock sediments contain fossils of different life-forms in different sedimentary layers indicates the geological period in which they existed. Embryological Evidences : Ernst Haeckel proposed Biogenetic Law Ontogeny recapitulates phylogeny. It means each individuals repeats their evolutionary history during their embryological development. (Ontogeny Individual development, Phylogeny species development) The Protonema, an early stage in the development of moss or fern gametophyte, resembles the filamentous green algae in structure, physiology and growth pattern. This suggests an algal ancestry of bryophytes and pteridophytes. The gymnosperms have normally become independent of water in fertilisation. However, the primitive gymnosperms such as Cycas and Ginkgo have flagellated sperms and need water for fertilization just like the pteridophytes, their most likely ancestors. 65

67 The seedlings of acacia tree initially develop simple leaves, but the leaves that develop later are compound. Molecular evidence in Evolution The degree of similarity in the base sequence in their nucleic acids, and amino acid sequence in their proteins are indicated. Human DNA differs in only 1.8% of its base pairs from chimpanzee DNA. There is no difference between the two in the amino acid sequence for the protein cytochrome C. Similarity in the molecular structure of actin and tubulin proteins in all animals point to their common ancestry. Comparative anatomy & morphology : Refer Fig.7.3, page 131 NCERT. 66

68 Anthropogenic Action : Before 1850 After 1920 More white winged moth in urban areas than dark winged or melanised moth. Less white winged moth in urban areas than dark winged or melanised moth. No industrialization Industrial revolution occur Tree trunk white color Tree trunk colour- dark Predators attack on dark moth than white. Predators attack on white moth than dark. Moths are able to camouflage themselves, i.e. hide in the background, survived. This type of evolution is due to anthropogenic action. Lichen act as a industrial pollution indicator. Excess use of herbicides, pesticides, antibiotics etc. develops resistant organisms / cells are appearing in a time scale of months or years and not centuries. Adaptive radiation The evolutionary process which produces new species from single point origin and spread to other geographical areas (habitat) is called adaptive radiation. Eg. Darwin finces found in Galapagos Island and Australian Marsupials. Darwin finches Thirteen species of finch evolved on the Galapagos Islands, all of them descendants of a single species of finch native to South America. Australian Marsupials. They change their food habit to avoid competition so their beak is modified according to their feeding habits like fruit, insect, seed, bark, new leaves, algae etc. Biological Evolution: 67

69 Darwin wrote a book origin of species by natural selection in According to Darwin, evolution is a natural selection takes a million of year. In microbes, new species forms in few days because they form new million of individuals in a day. Acc. to Darwin, Nature selects for fitness and it is based on characteristics which are inherited. Branching descent and natural selection are the two key concepts of Darwinian Theory of evolution. According to him all the species inhabiting earth today descended from ancestral species (descent with modification) and natural selection is the mechanism for such descent with modification. Natural Selection states that a population of organisms can change over the generations if individuals having certain heritable traits leave more offspring than other individuals, resulting in a change in the populations genetic composition over time. MECHANISM OF EVOLUTION : Darwinism Hugo de Vries Evolution is small. It is directional. Mostly beneficial Slow process (many steps) Evolution is small. It is random / non directional. Mostly harmful to organism. Single step large mutation (saltation) Hardy-Weinberg principle: allele frequencies in a population are stable and is constant from generation to generation. The gene pool (total genes and their alleles in a population) remains a constant. This is called genetic equilibrium. Sum total of all the allelic frequencies is 1. Individual frequencies, for example, can be named p, q, etc. In a diploid, p and q represent the frequency of allele A and allele a. The frequency of AA individuals in a population is simply p2 and frequency of aa is q2. p2 + 2pq + q2 = 1 or, (p + q)2 = 1 Calculation of allele frequencies Recessive traits: If the frequency of a recessive trait such as cystic fibrosis or PKU is known, it is possible to calculate allele frequencies and genotype frequencies using the Hardy Weinberg equation and its assumptions are as follows: i. say 1 in 1, 2500 Indian newborns have cystic fibrosis which means that the frequency of homozygotes for this recessive trait is q² = 1/2,500 = ii. The square root of the frequency of recessives is equal to the allele frequency of the cystic fibrosis allele q = (0.0004)0.5 = 0.02 iii. The frequency of the normal allele is equal to 1 - the frequency of the cystic fibrosis allele p = 1- q = = iv. The frequency of carriers (heterozygotes) for the cystic fibrosis allele is 2pq = 2 (0.98)(0.02) = 0.04 or 1/25 68

70 v. The frequency of homozygotes for the normal allele is p² = (0.98)² = 0.96vi. Thus the population is composed of three genotypes at the calculated frequencies of homozygous normal = 0.96, heterozygous carriers = 0.04, homozygous affected = Five factors are known to affect Hardy-Weinberg equilibrium : Gene migration or gene flow- emigration, immigration. Genetic drift : Sudden changes in polulation Mutation : sudden changes in DNA Genetic recombination : crossing over Natural selection. Sometimes the change in allele frequency is so different in the new sample of population that they become a different species. The original drifted population becomes founders and the effect is called founder effect. Original drifted population becomes founders and the effect is called founder effect. MODERN SYNTHETIC THEORY OF EVOLUTION Darwinism, the theory of natural selection has a wide acceptance. However, it has been criticised too, on the ground it could not explain how the variations arise. With progress in genetics, the sources of variation were explained and Darwin s theory was modified. Now, the most accepted theory of evolution is known as SYNTHETIC THEORY OF EVOLUTION, in which the origin of species is based on the interaction of genetic variation and natural selection. Natural selection causes allele frequencies of a population to change. Depending upon which traits are favoured in a population it can produce three different results. (1) Stabilizing selection - If both the smallest and largest individuals contribute relatively fewer offspring to the next generation than those closer to average size do, then stabilizing selection is operating. It reduces the variation but does not change mean value. (2) Directional selection If individuals at one extreme of the size distribution e.g. (the larger ones) contribute more offspring to the next generation then the other individuals do, then the mean size of individuals in the population will increase. In this case directional population is operating. If directional selection operates for many generations, an evolutionary trend within the population results. 69

71 (3) Disruptive selection- When natural selection simultaneously favours individuals at both extremes of the distribution, disruptive selection is operating. As a result we can see two peaks in the distribution of a trait. Ref. Fig. 7.8.page 136, NCERT. HUMAN EVOLUTION Time period Name Brain capacity Remarks Mya Dryopithecus (ape like) East Africa, Asia; closely related to chimpanzee Ramapithecus (man like) Shivalik Hills; erect posture, small canine 2 mya Australopithecines ( cave dwellers) 500cc African Ape Man ; height 1.5mts Homo habilis 700cc Tool Maker, Community Life 1.2 mya Homo erectus 800cc to 1300cc Knew how to use fire, larger teeth 100,000- Neanderthal man 1450cc East and central Asia 40,000 mya 25000mya Homo sapiens 1650cc Modern man ; height1.5 to 1.8 mts; flat face Synopsis of Human evolution Major Events during Geological Periods (Time scale): 70

72 PERIOD Precambrian: Cambrian Ordovician Silurian Devonian Carboniferous Permian Triassic Jurassic Cretaceous Tertiary Quaternary EVENTS Origin of life, Oxygen evolution through photosynthesis Flourishing of the invertebrates, increase in algal diversity, appearance of vertebrates. Plants begin to colonize land. Increase in diversity of fish. Amphibians appear Extensive forest, dominance of amphibians, increase in diversity of insects, first reptiles appear. Age of reptiles begin Dinosaurs evolve and spread, first mammal appear First bird and first flowering plant appear. Dominance of flowering plants. Age of mammals begin Evolution of human, Large mammals and birds become extinct. Organic Evolution Study Questions 1. Biological evolution is the cumulative changes that occur in a over time. 2. The principle source of change (genetic variation) is due to this type of chromosomal event. 3. Charles Darwin published his landmark book entitled in In his book, Darwin states that the origin of all life forms is due to random. 5. Darwin premise that all humans, animals, and bacteria share a common distant ancestor is explained with the concept of with. 6. Similarities of the structures between dissimilar species (ex: arm bones) are called structures. 71

73 7. Darwinian Theory tells us that + = new species 8. Neo-Darwinian Theory tells us that beneficial genetic mutations concentrated in a population over time can result in the formation of new. 9. List three characteristics that always provide a selective advantage. Evolution Study Questions KEY 1. Population. 2. Mutation 3. The Origin of Species 4. Chance. 5. Descent modification. 6. Homologous. 7. Mutability + natural selection = new species 8. Species. 9. i. self-defense ii. reproductive success iii. food gathering ability Probable questions: Short Answer Questions 1. Define evolution. 2. Explain the origin of the earth and atmosphere. 3.Who conducted simulation experiments? What is the significance of this experiment? Explain the simulation experiment conducted to explain the origin of complex organic molecules from simple molecules. Long Answer Questions 1. What are homologous organs? What is homology? What do the homologous organs explain as an evidence of organic evolution? 2. What are analogous organs? What is analogy? What do analogous organs explain as an evidence of organic evolution? 3. What are vestigial organs? How do they support the organic evolution? Name any four vestigial organs in human being. 4. Briefly explain the idea of natural selection taking industrial melanism or antibiotic resistance in bacteria as example. Ans. Prior to industrialization, number and frequency of white peppered moth far exceeded that of dark coloured peppered moth in Liverpool, England. Since the white moth got selective advantage over dark variety to avoid predation by concealing in the lichen infested grey tree trunk. However, after industrialization, due to disappearance of lichen in a polluted ambience the dark peppered moth got selective advantage over white moth to avoid predation in the black tree trunk and hence got reproductive success due to directional selection. A reduction in air pollution due to clean air legislation again lead to reproductive success of the white variety. ( industrial melanism) 5. What is geological time scale? How do you infer the evidence of evolution from it? 6. Discuss the evidences from morphology and comparative anatomy in support of organic evolution. 7. Comparative embryology gives no less a significant evidence in support of evolution than any other branch of biology. Substantiate. 8. Fossils are the documentary evidences in support of evolution. Discuss. 72

74 Ans Fossil record provides clear evidence for the evolution of species over time. It also documents the evolution of major new groups of organisms from previously existing organisms. Fossil records allow the biologist to reconstruct the history of life on earth. 9. Justify the statement" Galapagos islands are the living laboratories of Evolution". Ans The Galapagos island are home to 13 species of finches which evolved on the Galapagos island in isolation from other finches. New species of finches evolved from the single species that originally colonized the island provide unique example of adaptive radiationthus, supporting evolution. 10. What is Hardy-Weinberg equilibrium? Write the Hardy-Weinberg equation. 11. What is genetic drift? Ans :Genetic drift is the effect of chance. Genetic drift causes random changes in allele frequencies over time. Genetic drift can cause small populations to lose genetic variation. It can cause the fixation of harmful, neutral or beneficial alleles. 12. Define founder effect. Ans Founder effect is a genetic bottle neck that results when a small group of individuals from a larger source population establish a new population far from the original population. 13. What is gene flow? Ans. Gene flow is nothing but exchanging alleles between populations. Gene flow can introduce new alleles into a population, providing new genetic variation on which evolution can work. Gene flow makes the genetic composition of populations more similar 14. Discuss Darwin's theory of Natural Selection. Ans. Natural selection is the effect of advantageous allele. In natural selection (NS), individuals that possess certain forms of an inherited phenotypic trait tend to survive better and produce more offspring than do individuals that possess other forms of trait. NS is the only evolutionary mechanism that consistently favors alleles that improve the reproductive success of the organism in its environment. 15. Discuss mechanisms of evolution. Ans. Genetic variation is the raw material of evolution. Individuals within the populations differ in morphological, behavioral and biochemical traits, many of which are under genetic control. Genetic variation provides the raw material on which evolution can work. Evolution can be summarized as a three step process- Mutations and genetic rearrangements caused by recombination occur at random. These random events then generate inherited differences in the characteristics of individuals in populations. Finally, mutation, gene flow, genetic drift and natural selection can cause allele frequencies to change over time. Of the four mechanisms of evolutionary change, mutation, gene flow and genetic drift are influenced by chance events, while, natural selection is a random process. 16. Write short notes on Darwin s finches. Ans: A divergent evolution has occurred in the ground finches of Galapagos islands situated equator, some 900 km west of equator. on the Good example of adaptive radiation illustrated by Charles Darwin. He 73

75 differentiated thirteen species of finches and grouped them into six main types. Finches in general possess stout, conical beaks adapted for crushing seeds. But they have undergone great diversification in their feeding habits. Accordingly shape and size of their beak has changed, ancestral finches on reaching different islands occupied all empty ecological niches in absence of competition and evolved into different species. 17. What are living fossils? Give examples. Ans: Living fossil is an informal term for any living species (or clade) of organism which appears to be the same as a species otherwise only known from fossils and which has no close living relatives. These species have all survived major extinction events, and generally retain low taxonomicdiversities. A species which successfully radiates (forming many new species after a possible genetic bottleneck) has become too successful to be considered a "living fossil". Example: Ginkgo, Whisk ferns (Psilotum), cockroach, coelacanth fish etc. 18. What are missing links? Ans: The transitional fossil forms which show characteristics of two different groups of living animals are called missing links. These are the fossil connecting links. Example: Seymouria is the missing link between amphibians and reptiles, archaeopteryx is between reptiles and birds. 74

76 CHAPTER 8 : HUMAN HEALTH AND DISEASE 75

77 Name of the Disease Typhoid Pneumonia Name of the pathogen Salmonella typhi (diagnosed by Widal test) Streptococcus pneumonia and Haemophilus influenzae Type Bacterial Bacterial Transmission Symptoms Food & water borne Air, sharing glasses and utensils etc. Common cold Rhino Virus Viral Air & contact with infected person Malaria Amoebiasis Plasmodium(P. vivax, P. malariaand P. falciparum) Entamoeba histolytica Protozoan Protozoan Ascariasis Ascaris lubricoides Roundworm (Helminthes) Elephantiasis or Filariasis Ringworm Wuchereria (W. bancrofti and W. malayi), Microsporum, Trichophyton and Epidermophyton filarial worms Fungi Female Anopheles mosquito House fly, food & water. Soil, water, plant Culex female mosquito Soil & direct contact AIDS HIV Viral Transfusion of body fluids, unprotected sex etc. Sustained high fever (39 to 40 C), weakness, stomach pain, constipation, headache and loss of appetite the alveoli get filled with fluid leading to severe problems in respiration, fever, chills, cough and headache, lips and finger nails may turn gray to bluish in colour Nasal congestion and discharge, sore throat, hoarseness, cough, headache, Tiredness. Periodic high fever, chilled & shivering. constipation, abdominal pain and cramps, stools with excess mucous and blood clots internal bleeding, muscular pain, fever, anemia and blockage of the intestinal passage Lymphatic vessels of lower limbs are swollen. Genital organs are also often affected, resulting in gross deformities. Appearance of dry, scaly lesions on various parts of the body such as skin, nails and scalp Decrease immunity results to attack other pathogens like Toxoplasma, Mycobacterium, fungal, viral etc. 76

78 Sprozoites are injected into the body by female anopheles mosquito Sporozoite reach theliver through blood Parasite reproduces asexually in the liver and comes out in the blood by bursting theliver cells They enter the RBC PARASITE REPRODUCE ASEXUALLY IN RBC and by bursting them releases haemozoin which causes cycles of fever Released parasite enter new RBC and infect them Parasite starts the sexual stage and forms gametocytes in RBC Female aanopheles mosquito takes up gametocytes Fertilization of gametes and development takes place in the mosquitoes intestine Mature infective sporozoite escape from the intestine and migrate to the salivary glands of mosquito Mosquito bites again and injects the sprozoites into human body. LIFE CYCLE OF PLASMODIUM ON DUAL HOST (HUMAN & FEMALE ANOPHELES MOSQUITO) Personal and public hygiene Personal Hygeine Public Hygiene keeping the body clean consumption of clean drinking water, food, vegetables, fruits, etc. proper disposal of waste and excreta periodic cleaning and disinfection of water reservoirs, pools, cesspools and tanks and observing standard practices of hygiene in public catering Control of insect vector : Avoiding stagnation of water in and around residential areas, regular cleaning of household coolers, use of mosquito nets introducing fishes like Gambusia in ponds that feed on mosquito larvae, spraying of insecticides in ditches, drainage areas and swamps, etc. doors and windows should be provided with wire mesh to prevent the entry of mosquitoes. Vaccination and Immunization Vaccination refers to the administration of any vaccine. Immunization is the process by which the body produces antibodies in response to the vaccine to fight infections. 77

79 Vaccine is a preparation of antigenic proteins of pathogens or inactivated/weakened pathogen. It is introduced into the body to generate antibodies which can neutralize the pathogens during actual infection. Vaccines also generate memory B & T cells that recognize the pathogens quickly. Vaccines that contain performed antibodies produce quick immune response and provide Passive Immunity e.g. vaccines against tetanus & snakebite. Other vaccines provide Active Immunity e.g. oral polio vaccine, BCG, cholera vaccine. IMMUNITY Ability of the body's immune system to protect the body from disease INNATE IMMUNITY CHARACTERSTICS FEATURES 1.NON SPECIFIC 2.PRESENT AT THE TIME OF BIRTH ACTIVE ACQUIRED IMMUNITY PASSIVE TYPES OF BARRIERS 1. PHYSICAL BARRIER - SKIN 2. PHYSIOLOGICAL BARRIER - HCL & SALIVA 3. CELLULAR BARRIER - W.B.C,MACROPHAGE 4. CYTOKINE BARRIER - INTERFERON CHARACTERSTICS FEATURES 1.SPECIFICITY 2.DIVERSITY 3.DISTINGUISH BETWEEN SELF NON SELF 4.MEMORY 5.ACQUIRED DURING LIFETIME CELLS OF AQUIRED IMMUNITY (LYMPHOCYTE) T-LYMPHOCYTES 1. HELP B-CELLS TO PRODUCE ANTIBODY 2.DIRECTLY ATTACKS PATHOGENS 3.RETAINS MEMORY B-LYMPHOCYTE 1.PRODUCE ANTIBODY IN RESPONSE TO PATHOGEN (ANTIGEN) 78

80 ANTIBODY STRUCTURE TYPES OF ACQUIRED IMMUNITY ACTIVE IMMUNITY PASSIVE IMMUNITY - Antibody produced within own body - it is long lasting - Does not Cause allergy - Takes time to activate - Antibodies transferred from another individual. - Not long lasting. - Sometimes cause allergy -Provides immediate relief. Lymphoid Organs Primary Lymphoid Organ 1. Bone Marrow 2.Thymus Secondary Lymphoid Organ 1. Spleen 2. Lymph Nodes 3. Peyer s Patch 4. Tonsils 5. Mucosal associated lymphoid tissue (MALT) Function: Provide microenvironment For the development and Maturation of lymphocyte Function: 1. Spleen: Filter the microbes from blood 2. Lymph Nodes: Trap the microorganisms 3. Peyer s Patch: Present in small intestine and help In the formation of effector celles 4. Tonsils: Trap microbes entering through Mouth 5. MALT: Traps Microbes 79

81 Types of Immune Response Primary Response Secondary Response - Exposure of body to pathogen for first time - Of Low Intensity - Subsequent exposure to same pathogen - Response of body is hieghtened Allergy Common allergens (Substances that cause allergy Eg:- Dust,Pollen,Fur Some foods, some Chemicals) Symptoms Sneezing Running nose Watery eyes Itching Ways to reduce allergy Antihistamine Adrenaline Steriod Auto-immunity Condition when structural & functional damage is caused due to the attack of the self cells of the body by its own immune cells. Examples : Rheumatoid arthritis, Insulin- dependent diabetes. 80

82 CANCER CAUSES DETECTION TREATMENT IONISING RADIATION CHEMICAL eg : TAR FROM, CIGARETTS VIRUS - PAPILLOMA HEREDITARY PREDISPOSITION BIOPSY AND HISTOPATHOLOGICAL STUDY C.T, M.R.I, X RAY SURGERY RADIATION SYSTEMIC : a] CHEMOTHERAPY b] HORMONTHERAPY c] MONOCLONAL ANTIBODY SUPPORTIVE CARE d) α INTERFERON Refer Fig. 8.6, page 155 NCERT 81

83 Addiction and Dependence : Addiction is a psychological attachment to certain effects such as euphoria and a temporary feelingof well-being associated with drugs and alcohol. Withdrawal syndrome :if regular dose of drugs/alcohol is abruptly discontinued. This is characterised by anxiety, shakiness, nausea and sweating, which may be relieved when use is resumed again. Prevention and Control Avoid undue peer pressure Education and counseling Seeking help from parents and peers Looking for danger signs Seeking professional and medical help 82

84 Chapter 8 human health and disease IMPORTANT QUESTION 1) Why do children of metro cities of India suffer from allergies and asthma? Ans (Hint.-Pollution ) 2) A patient has lost his immunity. 1.How does saliva and tear help to prevent bacterial infection? Ans: -saliva and tear contain lysozymes. -Lysozymes enzymes which digest the cell wall of bacteria -By lysing the cell wall, they kill bacteria and prevent their infection. 2. What is vaccination?how does it help to produce immunity? Ans:- Vaccination process of introducing a preparation of antigenic protein of the pathogens or weakened or killed pathogen in to the body. -The vaccines include quick multiplication of B and T-lymphocytes; some of them are stored as memory cells -The B-lymphocytes quickly produce antibodies, which neutralize the antigen during infection. 3.Write the full form of ELISA. Give an example of the clinical application of ELISA? Ans:--Enzyme Linked Immune Sorbent Assay. -ELISA test is used in the diagnosis of AIDS, hepatitis-band other STD s 4.What are the advantages of people being healthy? Ans-When people are healthy, A)They are efficient at work which consequently increases productivity and brings economic prosperity B)Health increases longevity. C)It reduces infant and maternal mortality 5.A) Name the respective forms in which the malarial parasite gains entry into I) Human body and Ii) Body of female Anopheles B) Name the hosts where the sexual and the asexual reproduction of malarial parasite occur respectively C) Name the toxin responsible for the appearance of symptoms of malaria in humans. Why do these symptoms occur periodically? Ans-(A) (i)-sporozoite (ii)gametocyte (B)-sexual reproduction in mosquito -asexual reproduction in human body. ( C) Haemozoin - Haemozoin is released when the RBC s rupture and release the pathogen -some cells of pathogen enter fresh RBC s and reproduce asexually and repeat the cycle; hence the symptoms appear periodically. Define innate immunity. Name and explain the category of barrier which involves macrophages. 83

85 Ans. Innate immunity refers to all those defence elements with which a person is born and are always available to protect the body. -Macrophages form part of the cellular barrier. -The cellular barrier includes the following specialized cells; (i) Polymorphonuclear leucocytes. (ii) Monocytes. (iii) Natural killer lymphocytes and (iv) Macrophages. - these cells phagocytose and destroy the invading microbes. 7. What is meant by writing H2L2 for an antibody? Name any four types of antibodies produced in our/human body? Ans. - Each antibody molecule has four peptide chains. - Of them, two are small and called light chains (L) and two of them are longer and called heavy chains (H); hence written as H2L2. The four types of antibodies are iga, ige, igg and igm. 8.How do normal cells get transformed into cancerous neoplastic cells? Mention the differences between viral oncogenes and cellular oncogenes. Ans.The transformation of normal cells into cancerous neoplastic cells is induced by physical, chemical and biological agents collectively called carcinogens; they lose the property of contact inhibition. Difference: Viral Oncogenes - These are the genes present in the oncogenic viruses, which effect oncogenic transformation of the cells they infect. 9(i) Explai n metast asis. Why is it fatal? Ans. (i) Metastasis is the property of tumor cells, which get separated from a tumor, spread to different sites in the body through body fluids and produce secondary tumors wherever they are lodged. Since secondary tumors are formed at several parts of the body, it is difficult to be diagnosed and treated; hence it is fatal. 10 (1 ) Lymphocytes are of two types why are they called so? A person was injured in a road accident and required an urgent immune response. What should be done? (ii) The lymphocytes are of two types B and T-cells. Why are they called so? (iii) A person has injured on a road accident and required an urgent immune response. Ans: (i) Those lymphocytes which undergo maturation in the bone marrow are called B-cells while those which undergo maturation in the thymus are called T-cells. (ii) Those lymphocytes which undergo maturation in the bone marrow are called B-cells while those which undergo maturation in the thymus are called T-cells. (iii) Vaccine against Tetanus. HOTS Cellular Oncogenes - These are the genes present in normal cells and code for growth factors; when activated under certain conditions, can cause oncogenic transformation of the cell. 1 The immune system of a person is suppressed. In ELIZA test he tested positive i) Name the diseases associated with it. iii)why did he loose his immunity. Ans (Hint:-AIDS) 2 Which organ can trap the microbes in the body fluid? Lymph claimed that he has seen sounds, heard colours and smelt light. I)What could be the possible reason? Ii) Name two chemicles responsible for this conditions. Iii) Mention any one source for these chemicals. Ans (Hint:- Drug Abuse) 3)A person 84

86 Chapter-9 strategies for enhancement in food production Animal Breeding-objectives: Improved growth rate. Increased production Improve desirable qualities. Improved resistance to diseases Improved resistance to adverse environmental conditions BEE KEEPKING : Apis indica Bee-keeping or apiculture is the maintenance of hives of honeybees for the production of honey. Honey is a food of high nutritive value and also use in the indigenous systems of medicine. Honeybee also produces beeswax, which finds many uses in industry, such as in the preparation of cosmetics and polishes of various kinds. The following points are important for successful bee-keeping: o (i) Knowledge of the nature and habits of bees, o (ii) Selection of suitable location for keeping the beehives, o (iii) Catching and hiving of swarms (group of bees), o (iv) Management of beehives during different seasons, and o (v) Handling and collection of honey and of beeswax. Bees are the pollinators of many of our crop species such as sunflower, Brassica, apple and pear. Keeping beehives in crop fields during flowering period increases pollination efficiency and improves the yield beneficial both from the point of view of crop yield and honey yield. 85

87 METHODS OF ANIMAL BREEDING : Inbreeding:- Inbreeding refers to the mating of more closely related individuals within the same breed for 4-6 generations.. Eg.- cows, buffaloes, poultry Outbreeding : crosses between different breeds are called outbreeding. In breeding depression- continued in breeding reduces fertility even productivity. A single outcross often helps to overcome inbreeding depression ii) Outbreeding- breeding between unrelated animals of two types 1.) Out crossing- mating within the same breed but not having ancestors. 2.) Crossbreeding- superior males of one breed are mated with superior females of another breed to get better progency.e.g.- cows of inferior breed with superior bull. Hisardale- is a new breed of sheep developed in Punjab by crossing Bikaneri Eves and Marano Rams. 3) Interspecific hybridization- male and female animals of two different species are mated. E.g.- mule is crossbreed of male donkey and female horse. 4) Control breeding- it is done by artificial insemination and multiple ovulation embryo transfer technology (MOET) (a)artificial insemination- semen of superior male is collected and injected unto the reproductive tract of selected female. The spread of certain diseases can be controlled by this method. (b) MOET- Technique for herd improvement by successful production of hybrids. i) Hormone(FSH) are administered to the cow for inducing follicular maturation and super ovulation. ii) Cow produces 6-8 eggs instead of one egg & is either mated with elite bull or artificially inseminated. iii) Fertilised egg at 8-32 cell stage are recovered non-surgically & transferred to surrogate mother. iv) IDone in cattle, sheep, rabbits etc. Steps in Plant breeding:- 1 Collection of variability-collection and preservation of all different wild varieties, species, relatives of cultivated species etc. are also called germplasm collection. 2.Evaluation and selection of parents-germplasm is evaluated to identify plants with desirable traits. 3.Cross hybridization among the selected parents-two plants having two desired characters are hybridized to get new hybrid having two desired characters. 4.Selection and testing of superior recombinants-selection of the plants having desired character combinations. 5.Testing, release and commercialization of new cultivars-newly selected lines are evaluated for their yield, agronomic traits, disease resistance etc. and released into the market. Green revolution - Crop production. White revolution - Milk production Blue revolution - Fish production 86

88 CROPS AND RESISTANT VARIETIES LIST OF HIGH YIELD VARIETIES OF ANIMALS OF IMPORTANCE Sl. Animal Name of breed Distribution No. 01. Cattle Gir Gujrat Malvi Rajasthan Tharparkar Andhra Pradesh 02. Buffaloes Murrah Punjab Bhadawari Uttar Pradesh 03. Sheep Nali Jammu & Kashmin Shahabadi Bihar 04. Chicken Aseel India Rhode Island Red USA 05. Honey Bee Apis indica India Apis mellifera Italy 87

89 LIST OF HIGH YIELD VARIETIES OF PLANTS OF IMPORTANCE Sl. Plants Name of breed Distribution Type of varieties No. 01. Rice IR-8 Philippines Semi-dwarf Taichung Native-1 Taiwan Semi-dwarf Jaya India Semi-dwarf Ratna India Semi-dwarf 02. Wheat Sonalika India High yield Kalyan sona India Disease resistant Hidden Hunger : Deficiency of protein and vitamin is called hidden hunger because they cannot afford to buy enough fruits, vegetables, legumes, fish and meat. Biofortification-Breeding crops with higher levels of proteins, vitamins and minerals eg. Wheat variety Atlas- high content of protein, Vitamin A rich golden rice, Vit C rich bitter gourd, mustard, tomato; protein rich beans lablab etc. SCP (Single cell protein )- Protein rich cell biomass from microbes such as bacteria, yeast, algae are used as alternative food. Eg-Spirulina can be grown in waste water (from potato processing plant) to produce protein rich biomass treated as food. Advantages : i) Provides protein rich food supplement in human diet ii) Reduces pressure of conventional agricultural production iii)use of Waste water reduces pollution leveliv) High rate of biomass production in large amount in short period. Tissue culture- Technique of in vitro regeneration of whole plant by growing any plant part called explant in culture medium under aseptic condition. includes following methods: 1.Callus culture: Cell division in explant form an unorganized mass of cell called callus. 2. Suspension culture: Involves small group of cells suspended in a liquid media. 3..Meristem Culture Apical shoot meristem is used as explant & support multiple shoot development. 4.Embryo Culture:Excision of young embryos from developing seeds & culture in nutritional media. 5.Anther culture:production of haploid plant species by desired anther cultured in suitable medium. 6. Protoplast culture and somatic hybridization- In this method, hybridization of different species could produce variants of economic value as follows: Isolation of desired single cells Digestion of cell wall by pectinase & cellulase enzyme for exposure of protoplast Fusion of protoplast by Polyethylene glycol(peg) Hybrid protoplast culture resulting in desired variety of plant eg., Pomato is obtained by somatic hybrid of potato and tomato. 88

90 7.Micropropagation- Tissue culture technique used for rapid vegetative multilication of ornamental plants and fruit trees by using small explants. Micropopagation is done by shoot meristem culture & somatic embryogeny. It results in genetically identical plants & used widely in forestry & floriculture. Somaclonal variation-genetic variation in plants regenerated from a single culture is used to develop several useful varieties eg., Short duration sugarcane, Rust resistant wheat. Uses: a)rapid clonal multiplication b)production of virus free plants c)production of transgenic plants d)germplasm collection Questions I MARK Q1.Name two techniques involved in controlled breeding experiments. Q2.What is blue and green revolution? Q3. What is inbreeding depression? Q4. What is Heterosis or hybrid vigour? Q5.Name the Indian variety of rice patented by an American company. Q6.What is Pomato? Q7.Name the algae used as protein rich food. Q8.Expand- MOET and SCP. Q9.What is quarantine? Q10.What is cultivar? 2 MARKS Q1. What is Biofortification? Q2.Which part of the plant is best suited for making virus free plants? Q3.What is breed? What are the objectives of animal breeding? Q4.Define out-crossing? Suggest an advantage. Q5.What is artificial insemination? What is its importance? Q6. What are the differences between aqua and pisciculture? Q7. What is animal husbandry? Q8. What is bird flu? Q9. Name the most common species of honey bees of India? What are the products from the honey bees? Q10. What is germplasm? How it is maintained? 3 MARKS QUESTIONS Q1.What does inbreeding mean? Suggest its advantages. What is the danger of inbreeding? Q2.Name the methods employed in animal breeding. Which method is the best? Why? Q3. Explain the procedure of MOET technique in cattle. 89

91 Q4. What is interspecific hybridization? Give one example of crop in which it is practiced and mention one advantage. Q5. What is cross-breeding? What advantages does it have? Give an example 5 MARKS QUESTIONS Q1. Explain the points that have to be considered for successful bee- keeping? Q2. Write the scientific name of sugarcane grown in north and south India respectively. Mention their characteristic features. Mention the characteristic of the hybrid produced by crossing these two varieties. Hint :North Saccharumbarberi. South Saccharumofficinarum. High yield,thick stems, higher sugar content, ability to grow in both North and South India Q 3. Describe various steps involved in plant breeding. Hint: Collection of variability, Evaluation and selection of parents, Cross hybridisation among the selected parents, Selection of testing of superior Recombinants, Testing, release and comercialisation of new cultivars 90

92 Chapter 10: Microbes in Human Welfare Microbes are present everywhere. Thermal vents of geyser (Temp. above c) Deep in soil. Under snow. Microbes in household products S. No Microbes Causative organism Action product 1 Bacteria Lactobacillus Convert milk into curd Curd with increased vitamin B-12 2 Yeast Saccharomyces cerevisiae 3 Bacteria Propionibacterium sharmanii Fermentation Production of carbon di oxide Baker s yeast Swiss cheese Microbes in industrial products- S.No Microbes Causative organism product 1 Fungi Penicillium notatum Antibiotics 2 Yeast Saccharomyces Alcohol cerevisiae 3 Fungus Aspergillus niger Citric acid 4 Bacteria Acetobacter Acetic acid 5 Bacteria Clostridium butylicum Butyric acid 6 Bacteria Lactobacillus Lactic acid Enzymes and other bioactive molecules S. No Microbes Enzymes Products 1 Streptococcus (bacterium) Streptokinase Clot buster 2 Trichoderma polysporum (fungi) Cyclosporin A Immunosuppressive agent 3 Monascus purpureus (yeast) Statins Blood cholesterol lowering agents Enzymes and their actions S.No Enzymes Action 1 Lipase Removing oily strains 2 Pectinase Clarified bottled juices MICROBES IN SEWAGE TREATMENT 91

93 Waste water PRIMARY TREATMENT SECONDARY TREATMENT/BIOLOGICAL TREATMENT FILTRATION AERATION TANKS SEDIMENTATION formation of FLOCS (masses of bacteria associated with fungal filaments ) Significantly reduces BOD PRIMARY SLUDGE (SOLID SETTLE) AND SUPERNANTS FORMS EFFLUENTS SETTLING TANK Sediments called ACTIVATED SLUDGE ANAEROBIC SLUDGE DIGESTERS During digestion, bacteria produce mixture of gases such as METHANE, HYDROGEN SULPHIDE AND CARBON DIOXIDE 92

94 MICROBIAL USES HOUSE HOLD LAB- Starter, milk to Curd Check Disease causing microbes & Vit. B12 synthesis. Baker Yeast : Toddy (palm),swiss Cheese : Bacteria (Probionibacterium sharmanii); Roquefert Cheese - Fungi INDUSTRIAL Fermented Beverages * With Distillation (Whisky Brandy, Rum) * Without Distillation (Beer & wine) Antibiotic Production Penicillin & its history. Streptomycin,Tetracycline Bio-Control Chemical Production Type Name Product Bacteria- Acetobacter Acetic Acid Fungi Aspergillus niger Citric Acid Bacteria Clostridium Butyric Acid Bacteria Lactobacillus Lactic Acid Bt Caterpiller, aphids Ladybird aphid, mosquitoes Trichoderma viridae- fungal disease Nucleopolyhedral Virus : Insects & Arthropods ; IPM BIOFERTILIZERS Organic Farming Symbiotic Association- Rhizobium Free Living- Azatobactor, Azospirillium Mycorrhiza- Glomus (P absorb) Cynobacteria- Anabaena, Nostoc Enzyme : Lipase : as detergent for removing oily stains Pectinase & Protease : Juice clarifier. Streptokinase (Streptococcus) : Clot Buster of Myocardial diseases. Bioactive Compounds Organism Compund Name Use Trichoderma polysporum (Fungi) Cyclosporin Immunosuppresive (Organ transplant) Monascus purpureum (Yeast) Statin A Blood Cholesterol lowering agent 93

95 Biogas plant: Concrete tank mts deep, slurry or dung fed. Floating cover placed above rises as biogas content rises. Connecting pipe for supply of biogas. Used for cooking and lighting. Development by IARI :- Indian Agriculture Research institute & KVIC:-Khadi and village Industries Commission. Microbes as Biocontrol Agents : Insecticides and Pesticides toxic, harmful & are pollutants. Natural predation better method. No of pests kept in check, not totally eradicated. Food chains not disturbed Eg. Ladybird and Dragon flies useful to get rid of aphids and mosquitoes. Bacillus thuringiensis (Bt) used to control butterfly caterpillar. Mode of spores operation. Available is sachets, mixed with water and sprayed on plants. Eaten by insect larva Toxin released in gut kills larvae. Now Bt toxin genes introduced into plants resistant to insect pests. e.g. Bt cotton. Tungus trichoderma now being developed. Nucleo polyhedrovirus good for narrow spectrum insecticide applications. Advantages :- No negative impacts on plants, mammals, birds, fish or target insects. For overall IMP (Intergrated pest Management) programme. For ecologically sensitive areas. As Biofertilizers: Chemical fertilizers major pollutant. Switch to organic farming and use of biofertilizers need of the time. Main sources of biofertilizers. Bacteria, Fungi & Cyanobacteria. Eg Rhizobium present in roots of leguminious plants fix atmospheric nitrogen into usable organic form. Azospirillium and Azotobacter free living bacteria fix atmospheric Nitrogen. Symbiotic Associations Eg.Genus Glomus sp. form mycorrhiza Fungal symbiont absorbs phosphorus from soil and passes it to plant. Plants show resistance to root borne pathogens. Tolerance to salinity and drought 94

96 Increase in growth and development. Cynobacteria autotrophic fix atmospheric nitrogen Eg. e.g. Anabaena, Nostoc, Oscillatoria. Blue green algae increase fertility by adding organic matter. For production of biodegradable plastics: biodegradable plastic, e.g. polyhydroxybutyrate (PHB) is being produced commercially by fermentation with the bacterium Alcaligenes eutrophus. Production of PHB may be easily achieved in tree plants like populous, where PHB can be extracted from leaves. Other main drawback of bacterial PHB is its high production cost, making it substantially very expensive than synthetic plastics. As edible vaccines: The genes encoding the antigenic proteins of virus and bacteria can be isolated from the pathogens and expressed in plants. Such transgenic plants or their tissues producing antigens can be eaten for vaccination/immunization (edible vaccines). The expression of such antigenic proteins in crops like banana and tomato are useful for immunization of humans since banana and tomato fruits can be eaten raw. Example: cholera and hepatitis B vaccine. Process of sewage treatment in STP Primary treatment (physical) Filtration & sedimentation Secondary treatment (biological) Filtration &sedimentation Agitation & rapid growth of aerobic microbes (flocs) Consumes organic matter, reduces BOD Effluent passed to settling tank Flocs sediments form activated sludge Anaerobic Sludge Digester Form Biogas Water released into rivers and streams 95

97 QUIZ TIME : 96

98 Questions (1 mark) 1. Name two vitamins produced by microbial fermentation. 2. What is the botanical name of baker s yeast? 3. Milk starts to coagulate when lactic acid bacteria is added to warm milk as a starter. Mention two benefits LAB provides. 4. Name any two antibiotics produced from microbial action. Ans: Penicillin Penicillium notatum Streptomycin- Streptomyces griseus 5. Name any two human therapeutic proteins produced in bacteria. Ans: human insulin, hepatitis B surface antigen, human growth hormone, interferons etc. (2 marks) 1. State the use of: Trichoderma with respect to organ transplant ct to pest management 2. Why should sewage be treated before its disposal? 3. What is primary sludge? 4. Name the pests, lady birds and dragonflies help to get the rid of respectively 5. Give the role of microbes in single cell protein. 6. What is micorrhiza? How does it help as biofertilizers? 7. What is BOD? What does it mean if a water sample has more BOD? 8. Name any two Cyanobacteria. How do they serve as main source of biofertilizer? 9. What is the difference between Bt and Bt cotton? Explain the use of Bt as a biological control. 10. Give reasona) Bottled fruit juices brought from market are clearer as compared to those made at home, b) Large holes are found in swiss-cheese, c) The insect which are so called pest are not eradicated in organic fumes. 11. Name the gobar gas liberated from biogas plant. Which type of bacteria are responsible for its production? Give advantage. 12. What do you mean by GRAS? Ans: GRAS means generally regarded as safe category which includes microbes which are non-pathogenic, non-toxic, non-antibiotic producing etc. These are generally used as hosts for production of recombinant molecules. 14. What is Golden Rice? In what why is it different from normal rice? Ans: The staple food rice is extremely low in vitamin A and therefore the improvement of vitamin A required. Prof. Ingo Potrykus and Dr. Peter Beyer developed genetically engineered rice which is enriched in provitamin A (beta-carotenoid) by introducing three genes involved in the biosynthetic pathway for carotenoid. It is called golden rice, the seeds are yellow in colour because of pro-vitamin A is produced in the entire grain. 15. What do you mean by flavr savr tomato? 97

99 Ans: These are transgenic tomatoes commercialized in U.S with longer shelf life due to slow ripening. Gas hormone, ethylene is involved in the regulation of fruit ripening. Therefore, ripening can be slowed down by blocking or reducing ethylene production. (3 marks) 1. Differentiate between a) Primary sludge and activated sludge, b) Biofertilizer and chemical fertilizer, c) Primary sewage treatment and secondary sewage treatment. (5 marks) 1.Answer briefly: 1) How is sewage harmful to man? 2) What is organic farming? 3) Which group of organisms attack insect and arthropod? How are they best biocontrol biological agent, 4) What is the difference between flocks and primary sludge? 2.Write short notes on: a) baker s yeast, b) alcohol c) statin d) brewer s yeast e) streptokinase 98

100 Chapter-11: BIOTECHNOLOGY: PRINCIPLES AND PROCESSES Biotechnology is a broad area of science involving multiple disciplines designed to use living organisms or their products to perform valuable industrial or manufacturing processes or applications pertaining to human benefit. Recombinant DNA technology: An organism's genome contains virtually all the information necessary for its growth and development Steps in producing recombinant DNA 1. The required gene is cut from a DNA molecule using a restriction enzyme. 2. A bacterial plasmid is isolated and cut with the same restriction enzyme. This ensures cut ends are complementary (same base sequence) to the ends of the required gene. 3. The required gene is joined to the plasmid using the enzyme DNA ligase in a process called ligation. 4. The resulting recombinant plasmid is returned to the bacterial cell. 5. The bacteria reproduce and the required gene is cloned. Quite straightforward to isolate DNA For instance, to isolate genomic DNA 1. Remove tissue from organism 2. Homogenise in lysis buffer containing guanidine thiocyanate (denatures proteins) 3. Mix with phenol/chloroform - removes proteins 4. Keep aqueous phase (contains DNA) 5. Add alcohol (ethanol or isopropanol) to precipitate DNA from solution 6. Collect DNA pellet by centrifugation 7. Dry DNA pellet and resuspend in buffer 99

101 8. Store at 4 C Each cell (with a few exceptions) carries a copy of the DNA sequences which make up the organism's genome. Recombinant DNA Technology Procedure : - Isolation - Digestion - Fractionation - Purification of the TARGET fragment - Cloning into vectors - Transformation of host cell and selection - Replication - Analysis Introduction of recombinant DNA into host cells: Some commonly used procedures: 1. Transformation 2. Transfection 3. Electroporation 4. Biolistics 5. Agrobacterium mediated gene transfer Discovery of a first restriction enzyme Hind II in the bacterium Haemophilus influenza by Nathans, Arbar & Smith and award Nobel Prize. Naming : Restriction enzymes the first letter of the name comes from the genes and the second two letters come from the species of the prokaryotic cell from which they were isolated. Like EcoRI comes from Escherichia coli RY 13. In EcoRI, the letter R is derived from the name of strain. Roman numbers following the names indicate the order in which the enzymes were isolated from that strain of bacteria. Restriction enzymes belong to a larger class of enzymes called nucleases. Types : Exonucleases remove nucleotides from the ends of the DNA whereas, endonucleases make cuts at specific positions within the DNA. Source microorganism Enzyme Recognition Site Ends produced Arthrobacter luteus Alu I AG CT Blunt Bacillus amyloiquefaciens H Bam HI G GATCC Sticky Escherichia coli Eco RI G AATTC Sticky Haemophilus gallinarum Hga I GACGC(N) 5 Sticky Haemophilus infulenzae Hind III A AGCTT Sticky 100

102 Providencia stuartii 164 Pst I CTGCA G Sticky Nocardia otitiscaviaruns Not I GC GGCCGC Sticky Staphylococcus aureus 3A Sau 3A GATC Sticky Serratia marcesans Sma I CCC GGG Blunt Thermus aquaticus Taq I T CGA Sticky Restriction enzymes recognise a specific short nucleotide sequence This is known as a Restriction Site The phosphodiester bond is cleaved between specific bases, one on each DNA strand The product of each reaction is two double stranded DNA fragments Restriction enzymes do not discriminate between DNA from different organisms Restriction endonucleases are a natural part of the bacterial defense system o Part of the restriction/modification system found in many bacteria These enzymes RESTRICT the ability of foreign DNA (such as bacteriophage DNA) to infect/invade the host bacterial cell by cutting it up (degrading it) The host DNA is MODIFIED by METHYLATION of the sequences these enzymes recognise Methyl groups are added to C or A nucleotides in order to protect the bacterial host DNA from degradation by its own enzymes 101

103 Types of restriction enzymes o o o Type I Recognise specific sequences but then track along DNA (~ bases) before cutting one of the strands and releasing a number of nucleotides (~75) where the cut is made. A second molecule of the endonuclease is required to cut the 2nd strand of the DNA e.g. EcoK. Require Mg 2+, ATP and SAM (S-adenosyl methionine) cofactors for function. Type II Recognise a specific target sequence in DNA, and then break the DNA (both strands), within or close to, the recognition site.only they are used in rdna technology as they recognize and cut DNA within a specific sequence typically consisting of 4-8 bp. e.g. EcoRI Usually require Mg 2+ Type III Intermediate properties between type I and type II. Break both DNA strands at a defined distance from a recognition site e.g. HgaI Require Mg 2+ and ATP Hundreds of restriction enzymes have been isolated and characterised Enables DNA to be cut into discrete, manageable fragments Type II enzymes are those used in the vast majority of molecular biology techniques Many are now commercially available Many Type II restriction endonucleases recognise PALINDROMIC sequences (From Greek palindromos, running back again, recurring :palin, again) A segment of double-stranded DNA in which the nucleotide sequence of one strand reads in reverse order to that of the complementary strand. (always read from the same direction) For example, EcoRI recognises the sequence 102

104 Different enzymes cut at different positions and can create single stranded ends ('sticky ends') Some generate 5' overhangs - eg: EcoRI Some generate 3' overhangs - eg: PstI Some generate blunt ends- eg: SmaI Examples of restriction enzymes and the sequences they cleave. The 'sticky' overhangs are known as COHESIVE ENDS This is the basis for RECOMBINANT DNA TECHNOLOGY Inserting foreign DNA into a cloning vector Restriction enzymes are a useful tool for analysing Recombinant DNA After ligating a particular DNA sequence into a cloning vector, it is necessary to check that the correct fragment has been taken up. Sometimes it is also necessary to ensure that the foreign DNA sequence is in a certain orientation relative to sequences present in the cloning vector. Checking the size of the insert Checking the orientation of the insert Determining pattern of restriction sites within insert DNA DNA fractionation Separation of DNA fragments in order to isolate and analyse DNA cut by restriction enzymes Electrophoresis Electrophoresis is a technique used to separate and sometimes purify macromolecules - especially proteins and nucleic acids - that differ in size, charge or conformation. When charged molecules are placed in an electric field, they migrate toward either the positive or negative pole according to their charge. 103

105 DNA is electrophoresed through the agarose gel from the cathode (negative) to the anode(positive) when a voltage is applied, due to the net negative charge carried on DNA. When the DNA has been electrophoresed, the gel is stained in a solution containing the chemical ethidium bromide. This compound binds tightly to DNA and fluoresces strongly under UV light - allowing the visualisation and detection of the DNA. Recombinant DNA technology: What is DNA cloning? Recombinant DNA: Plasmids, cloning DNA cloning is the isolation of a fragment or fragments of DNA from an organism and placing in a VECTOR that replicates independently of chromosomal DNA. The RECOMBINANT DNA is propagated in a host organism, the resulting CLONES are a set of genetically identical organisms which contain the recombinant DNA Three main purposes for cloning DNA 1) DNA sequencing 2) Protein production 3) Engineering animals/plants/proteins Cloning and Expression Vectors Isolated DNA is cloned into VECTORS for long term storage, propagation of the DNA and for production of protein from gene(s) encoded in the DNA What are cloning vectors? Cloning vectors are extra-chromosomal 'replicons' of DNA which can be isolated and can replicate independently of the chromosome. Vectors usually contain a selectable marker - a gene that allows selection of cells carrying the vector e.g. by conferring resistance to a toxin. DNA of interest can be cloned into the vector and replicated in host cells, usually one which has been well characterised. Commonly used vector systems Bacterial plasmids Bacteriophages Cosmids Yeast artificial chromosomes (YACs) 104

106 Ti plasmid (plants) Eukaryotic viruses such as baculovirus (insect cells), SV40 virus and retroviruses. Characteristics of a Cloning Vector Origin of replication (ORI) This process marks autonomous replication in vector. ORI is a specific sequence of nucleotide in DNA from where replication starts. When foreign DNA is linked to this sequence then along with vector replication, foreign (desirable) DNA also starts replicating within host cell. Selectable Marker Charecteristics of Selectable marker: A gene whose expression allows one to identify cells that have been transforrned or transfected with a vector containing the marker gene. A marker gene is used to determine if a piece of DNA has been successfully inserted into the host organism. Gene usually encoding resistance to an antibiotic. A selectable marker will protect the organism from a selective agent that would normally kill it or prevent its growth. Restriction sites Allow cleavage of specific sequence by specific Restriction Endonuclease. Restriction sites in E.coli cloning vector pbr322 include HindIII, EcoRI, BamHI, SalI, PvuI, PstI, ClaI etc. Refer NCERT text book diagram of pbr322 A Cloning Vector that Works with Plant Cells Most commonly used plant cloning vector "Ti" plasmid, or tumor-inducing plasmid. Found in cells of the bacterium known as Agrobacterium tumefaciens, normally lives in soil. Bacterium has ability to infect plants and cause a crown gall, or tumorous lump, to form at the site of infection. Ti plasmid - called T DNA - separates from the plasmid and incorporates into the host cell genome. This aspect of Ti plasmid function has made it useful as a plant cloning vector (natural genetic engineer). Plasmids are the most commonly used vector system. Several types available for cloning of foreign DNA in the host organism Escherichia coli. Many E. coli plasmids allow the expression of proteins encoded by the cloned DNA Bacteriophage another common vector system used for cloning DNA. These are viruses which 'infect' E. coli. The M13 bacteriophage is a single-stranded DNA virus which replicates in E. coli in a double-stranded form that can be manipulated like a plasmid. It can be used to produce single-stranded DNA copies which are useful for DNA sequencing. Bacteriophage common vector system used to make DNA libraries. It allows the cloning of larger fragments of DNA than can be incorporated into plasmids. Transformation is the process by which plasmids (or other DNA) can be introduced into a cell. For E. coli transformation with plasmids is quite straightforward. Plasmids can be introduced by electroporation or by incubation in the presence of divalent cations (usually Ca 2+ ) and a brief heat shock (42 C) which induces the E. coli cells to take up the foreign DNA 1. Two antibiotic selection and replica plating 2. Color selection: blue/white selection using the lacz gene 105

107 Insertional inactivation - Subcloning a DNA fragment into an active gene (usually a marker gene whose function can be easily detected) will disrupt the function of that gene. This can be detected by looking for colonies that no longer display that phenotype. Colour selection A more common method to determine which transformants contain plasmids with inserts is to use colour selection. For E. coli, this involves the lac complex and blue/white screening. Colonies carrying plasmid with no insert will be coloured blue whereas colonies carrying recombinant plasmid will be white. For plasmids such as pbr322, which contains two antibiotic resistance genes, cloning an insert into one of these will disrupt that gene and inactivate the resistance to that antibiotic. Southern/Northern Blotting : Analysing complex nucleic acid mixtures (DNA or RNA) The total cellular DNA of an organism (genome) or the cellular content of RNA are complex mixtures of different nucleic acid sequences. Restriction digest of a complex genome can generate millions of specific restriction fragments and there can be several fragments of exactly the same size which will not be separated from each other by electrophoresis. Techniques have been devised to identify specific nucleic acids in these complex mixtures Southern blotting - DNA Northern blotting - RNA Southern blotting Technique devised by Ed Southern in 1975, is a commonly used method for the identification of DNA fragments that are complementary to a know DNA sequence. Allows a comparison between the genome of a particular organism and that of an available gene or gene fragment ( probe). It can tell us whether an organism contains a particular gene (DNA fragment) or not In Southern blotting, 1. Chromosomal DNA is isolated from the organism of interest, and digested to completion with a restriction endonuclease enzyme. 2. The restriction fragments are then subjected to electrophoresis on an agarose gel, which separates the fragments on the basis of size. 106

108 3. DNA fragments in the gel are denatured (i.e. separated into single strands) using an alkaline solution. 4.Transfer fragments from the gel onto nitrocellulose filter or nylon membrane. DNA is bound irreversibly to the filter/membrane by baking at high temperature (nitrocellulose) or cross-linking through exposure to UV light (nylon). Final step is to immerse the membrane in a solution containing the probe - either a DNA (cdna clone, genomic fragment, oligonucleotide or RNA ) can be used. This is DNA hybridisation. The membrane is washed to remove non-specifically bound probe, and is then exposed to X-ray film - a process called autoradiography. The principle of Southern blotting. PCR(Polymerase Chain Reaction): PCR is a technique for the in vitroamplification of a desired sequence of DNA. PCR allows the 107

109 shown that PCR can be used to generate a detectable quantity of DNA from only one starting target (or template) molecule. PCR developed in the mid-1980's, has found multiple applications, such as: 1. Rapid amplification of intact genes or gene fragments 2. Generation of large amounts of DNA for sequencing 3. Generation of probes specific for uncloned genes by selective amplification of a specific segment of cdna 4. Analysis of mutations for medical applications 5. Detection of minute amounts of DNA for forensic purposes 6. Amplification of chromosomal regions adjacent to genes of known sequence and many more Development of PCR won the Nobel prize for Kary Mullis and co-workers. PCR principle PCR reaction is a DNA synthesis reaction that depends on the extension of primers annealed to opposite strands of a dsdna template that has been denatured (melted apart) at temperatures near boiling. By repeating the melting, annealing and extension steps, several copies of the original template DNA can be generated. The amount of starting material (target) needed is very small Not necessary to isolate the desired sequence, because it will be defined by the primers that are used in the reaction. The primers are oligonucleotides complementary to different regions on the 2 strands of DNA template (flanking the region to be amplified). The primer acts as a starting point for DNA synthesis. The oligo is extended from its 3' end by DNA polymerase. 108

110 PCR is a cycle of three steps: The stages of a PCR reaction 1. DENATURATION - the strands of the DNA are melted apart by heating to 95 C 2. ANNEALING - the temperature is reduced to ~ 55 C to allow the primers to anneal to the target DNA 3. POLYMERISATION / EXTENSION - the temperature is changed to the optimum temperature for the DNA polymerase to catalyse extension of the primers, i.e. to copy the DNA between the primers. The cycle is repeated over and over again - as many times as needed to produce a detectable amount of product. Discovery of a thermostable DNA polymerase The breakthrough came with the discovery of the thermostable DNA polymerase Taq polymerase, from the thermophilic bacterium, Thermus aquaticus, which lives in hot springs. Taq polymerase enzyme can resist high temperatures required to melt the template DNA apart without denaturation (loss of activity) and works best at high temperatures (72 C). This led to improved specificity & sensitivity. Annealing of primers to sites other than the target sequence is significantly reduced at the higher temperatures used for Taq polymerase. Applications of PCR 1) Cloning a gene encoding a known protein 2) Amplifying 'old DNA' 3) Amplifying cloned DNA from vectors 4) Creating mutations in cloned genes 5) Rapid amplification of cdna ends - RACE 6) Detecting bacterial or viral infection * AIDs infection 109

111 * Tuberculosis (Mycobacterium tuberculosis) 7) Cancer Detecting mutations that occur in cancer and monitoring cancer therapy. Determining if a patient is free of malignant cells 8) Genetic diagnosis a. Diagnosing inherited disorders * Cystic fibrosis * Muscular dystrophy * Haemophilia A and B * Sickle cell anaemia b. Diagnosing cancer - certain cancers are caused by specific and reproducible mutations: eg. Retinoblastoma - childhood cancer of the eye. The heritable form (germ line mutation of one of the two retinoblastoma allelles): mutation is detected in all cells. Spontaneous form: only detected in tumour tissue. c. Blood group typing d. Prenatal diagnosis eg determining the sex of foetus for those at risk of X-linked disorders PCR is one of the most versatile techniques invented, and has so many applications that this list could go on for quite some time. Downstream processing It refers to the recovery and purification of biosynthetic products, particularly pharmaceuticals, from natural sources such as animal or plant tissue or fermentation broth Stages in Downstream Processing A widely recognized heuristic for categorizing downstream processing operations divides them into four groups which are applied in order to bring a product from its natural state as a component of a tissue, cell or fermentation broth through progressive improvements in purity and concentration. Removal of insolubles Product Isolation Product Purification Product Polishing Antisense RNA technology An RNA molecule that is the reverse complement of a naturally occurring mrna, and which can be used to prevent translation of that mrna in a transformed cell. Autoradiography A technique that uses X-ray film to visualize radioactively labeled molecules or fragments of molecules; used in analyzing length and number of DNA fragments after they are separated by gel electrophoresis. Bacterial artificial chromosome (BAC) A vector used to clone DNA fragments (100 to 300 kb insert size; average, 150 kb) in Escherichia coli cells. Based on naturally occurring F-factor plasmid found in the bacterium E. coli. Bioinformatics The science of managing and analyzing biological data using advanced computing techniques. Especially important in analyzing genomic research data. Biolistics Remarkable method developed to introduce foreign DNA into mainly plant cells is by using a gene or particle gun. Microscopic particles of gold or tungsten are coated with the DNA of interest and bombarded onto cells 110

112 with a device much like a particle gun. Hence the term biolistics is used. Biotechnology Set of biological techniques developed through basic research and now applied to research and product development. In particular, biotechnology refers to the use by industry of recombinant DNA, cell fusion, and new bioprocessing techniques. Carrier An individual who possesses an unexpressed, recessive trait. cdna library A collection of DNA sequences that code for genes. The sequences are generated in the laboratory from mrna sequences. Clone An exact copy made of biological material such as a DNA segment (eg. a gene or other region), a whole cell, or complete organism. Cloning Using specialized DNA technology to produce multiple, exact copies of a single gene or other segment of DNA to obtain enough material for further study. Process, used by researchers in the Human Genome Project, referred to as cloning DNA. Resulting cloned (copied) collections of DNA molecules constitute clone libraries. Second type of cloning exploits the natural process of cell division to make many copies of an entire cell. The genetic makeup of these cloned cells, called cell line, is identical to the original cell. Third type of cloning produces complete, genetically identical animals such as the famous Scottish sheep, Dolly. Cloning vector DNA molecule originating from a virus, a plasmid, or the cell of a higher organism into which another DNA fragment of appropriate size can be integrated without loss of the vector's capacity for self-replication; vectors introduce foreign DNA into host cells, where the DNA can be reproduced in large quantities. Examples are plasmids, cosmids, and yeast artificial chromosomes; vectors are often recombinant molecules containing DNA sequences from several sources. Complementary DNA (cdna) DNA that is synthesized in the laboratory from a messenger RNA template. Complementary sequence Nucleic acid base sequence that can form a double-stranded structure with another DNA fragment by following base-pairing rules (A pairs with T and C with G). The complementary sequence to GTAC for example, is CATG. Cosmid Artificially constructed cloning vector containing the cos gene of phage lambda. Cosmids can be packaged in lambda phage particles for infection into E. coli; Permits cloning of larger DNA fragments (up to 45kb) than can be introduced into bacterial hosts in plasmid vectors. Crossing over The breaking during meiosis of one maternal and one paternal chromosome, the exchange of corresponding sections of DNA, and the rejoining of the chromosomes. This process can result in an exchange of alleles between chromosomes. See also:recombination Electrophoresis 111

113 A method of separating large molecules (such as DNA fragments or proteins) from a mixture of similar molecules. An electric current is passed through a medium containing the mixture, and each kind of molecule travels through the medium at a different rate, depending on its electrical charge and size. Agarose and acrylamide gels are the media commonly used for electrophoresis of proteins and nucleic acids. Electroporation A process using high-voltage current to make cell membranes permeable to allow the introduction of new DNA; commonly used in recombinant DNA technology. Embryonic stem (ES) cells An embryonic cell having totipotency that can replicate indefinitely, transform into other types of cells, and serve as a continuous source of new cells. These cells are derived from inner cell mass of the blastocyst or the 4-8 cell stage of embryo. Escherichia coli Common bacterium that has been studied intensively by geneticists because of its small genome size, normal lack of pathogenicity, and ease of growth in the laboratory. Exonuclease An enzyme that cleaves nucleotides sequentially from free ends of a linear nucleic acid substrate. Expressed sequence tag (EST) A short strand of DNA that is part of cdna molecule and can act as identifier of a gene. Used in locating and mapping genes. Fingerprinting In genetics, the identification of multiple specific alleles on a person's DNA to produce a unique identifier for that person. Fluorescence in situ hybridization (FISH) A Physical mapping approach that uses fluorescein tags to detect hybridization of probes with metaphase chromosomes and with the less-condensed somatic interphase chromatin. Forensics Use of DNA for identification. Some examples of DNA use are to establish paternity in child support cases; establish the presence of a suspect at a crime scene, and identify accident victims. Functional genomics Study of genes, their resulting proteins, the role played by proteins in the body's biochemical processes. Gene The fundamental physical and functional unit of heredity. A gene is an ordered sequence of nucleotides located in a particular position on a particular chromosome that encodes a specific functional product (i.e., a protein or RNA molecule) Gene expression The process by which a gene's coded information is converted into the structures present and operating in the cell. Expressed genes include those that are transcribed into mrna and then translated into protein and those that are transcribed into RNA but not translated into protein (eg. transfer and ribosomal RNAs). Gene gun or particle gun: a popular and widely used direct gene transfer method for delivering foreign genes into virtually any tissues and cells or even intact seedlings. The foreign DNA is coated or precipitated onto the surface of minute gold or tungsten particles (1-3 µm). 112

114 It is bombarded or shot onto the target tissue or cells using the gene gun or microprojectile gun or shot gun. The bombarded cells or tissues are cultured on selection medium to regenerate plants from the transformed cells. Gene mapping Determination of the relative positions of genes on a DNA molecule (chromosome or plasmid) and of the distance, in linkage units or physical units, between them. Gene therapy Experimental procedure aimed at replacing, manipulating, or supplementing nonfunctional or misfunctioning genes with healthy genes. Gene transfer Incorporation of new DNA into an organism's cells, usually by a vector such as a modified virus. Used in gene therapy. Genetic engineering Altering the genetic material of cells or organisms to enable them to make new substances or perform new functions. Genetic polymorphism Difference in DNA sequence among individuals, groups, or populations (e.g., genes for blue eyes versus brown eyes). Genetic testing Analyzing an individual's genetic material to determine predisposition to a particular health condition or to confirm a diagnosis of genetic disease. Genome project Research and technology-development effort aimed at mapping and sequencing the genome of human beings and certain model organisms. Genomic library A collection of clones made from a set of randomly generated overlapping DNA fragments that represent the entire genome of an organism. In situ hybridization Use of a DNA or RNA probe to detect the presence of the complementary DNA sequence in cloned bacterial or cultured eukaryotic cells. In vitro Studies performed outside a living organism such as in a laboratory. In vivo Studies carried out in living organisms. Knockout Deactivation of specific genes; used in laboratory organisms to study gene function. Microinjection 113

115 A technique for introducing a solution of DNA into a cell using a fine microcapillary pipette or microsyringe under a phase contrast microscope to aid vision. Microsatellite DNA Polymorphism comprising tandem copies of usually, two-, three-, four- or five-nucleotide repeat units, also called a short tandem repeat (STR). Northern blot A gel-based laboratory procedure that locates mrna sequences on a gel that are complementary to a piece of DNA used as a probe. Nucleotide A subunit of DNA or RNA consisting of a nitrogenous base (adenine, guanine, thymine, or cytosine in DNA; adenine, guanine, uracil, or cytosine in RNA), a phosphate molecule, and a sugar molecule (deoxyribose in DNA and ribose in RNA). Thousands of nucleotides are linked to form a DNA or RNA molecule. Nucleus The cellular organelle in eukaryotes that contains most of the genetic material. Phage A virus for which the natural host is a bacterial cell. Plasmid Autonomously replicating extra-chromosomal circular DNA molecules, distinct from the normal bacterial genome and nonessential for cell survival under nonselective conditions. Some plasmids are capable of integrating into the host genome. Number of artificially constructed plasmids are used as cloning vectors. Plaque A zone of clearing on a lawn of bacteria caused by lysis of the cells by infecting phage particles. Primer Short preexisting polynucleotide chain(generally from nucleotides in length) to which new deoxyribonucleotides can be added by DNA polymerase. Probe Single-stranded DNA or RNA molecules of specific base sequence, labeled either radioactively or immunologically. Used to detect the complementary base sequence by hybridization. Promoter The nucleotide sequence upstream of a gene that acts as a signal for RNA polymerase binding. Restriction enzyme, endonuclease Protein that recognizes specific, short nucleotide sequences and cuts DNA at those sites. Bacteria contain over 400 such enzymes that recognize and cut more than 100 different DNA sequences. Restriction fragment length polymorphism (RFLP) Variation between individuals in DNA fragment sizes cut by specific restriction enzymes; polymorphic sequences that result in RFLPs are used as markers on both physical maps and genetic linkage maps. RFLPs are usually caused by mutation at a cutting site. 114

116 Restriction-enzyme cutting site Specific nucleotide sequence of DNA at which a particular restriction enzyme cuts the DNA. Some sites occur frequently in DNA (e.g., every several hundred base pairs); others much less frequently (rare-cutter; e.g., every 10,000 base pairs). Retroviral infection Presence of retroviral vectors, such as some viruses, which use their recombinant DNA to insert their genetic material into the chromosomes of the host's cells. The virus is then propogated by the host cell. Reverse transcriptase Enzyme used by retroviruses to form a complementary DNA sequence (cdna) from their RNA. The resulting DNA is then inserted into the chromosome of the host cell. Reverse transcription-pcr (RT-PCR) PCR technique in which the starting material is RNA. The first step in the procedure is conversion of the RNA to cdna with reverse transcriptase. Satellite Chromosomal segment that branches off from the rest of the chromosome but is still connected by a thin filament or stalk. Sequencing Determination of order of nucleotides (base sequences) in a DNA or RNA molecule or the order of amino acids in a protein. The X or Y chromosome in human beings that determines the sex of an individual. Females have two X chromosomes in diploid cells; males have an X and a Y chromosome. The sex chromosomes comprise the 23rd chromosome pair in a karyotype. Shotgun method Sequencing method that involves randomly sequenced cloned pieces of the genome, with no foreknowledge of where the piece originally came from. This can be contrasted with "directed" strategies, in which pieces of DNA from known chromosomal locations are sequenced. Because there are advantages to both strategies, researchers use both random (or shotgun) and directed strategies in combination to sequence the human genome. Shuttle vector A vector that can replicate in the cells of more than one organism (e.g. YAC vector in E.coli and in yeast). Single nucleotide polymorphism (SNP) DNA sequence variations that occur when a single nucleotide (A, T, C, or G) in the genome sequence is altered. Southern blotting Transfer by absorption of DNA fragments separated in electrophoretic gels to membrane filters for detection of specific base sequences by radio-labeled complementary probes. Transgenic An experimentally produced organism in which DNA has been artificially introduced and incorporated into the organism's germ line. Vector 115

117 DNA molecule, capable of replication in a host organism, into which a gene in inserted to construct a recombinant DNA molecule. Western blot A technique used to identify and locate proteins based on their ability to bind to specific antibodies. Yeast artificial chromosome (YAC) Constructed from yeast DNA, it is a vector used to clone large DNA fragments. Questions 1 Mark Questions 1) What is biotechnology? 2) Define plasmid. 3) What are molecular scissors? 4) What do you mean by recognition sequence? 5) Which enzymes act as molecular glue? 6) What is elution? 7) What are cloning vectors? 8) Name the sequence within a cloning vector from where the replication commences. 9) Mention the bacteria that acts as natural genetic engineer. 10) Name any two processes by which alien DNA is introduced into the host cell. 11) Expand the term PCR. 12) Name the microorganism from which the thermostable DNA polymerase required for PCR is obtained? 13) What is a bioreactor? 14) What are the two main processes involved in downstream processing? 15) Do eukaryotic cells have restriction endonucleases? Justify your answer. HINTS: 1) Large scale production and marketing of products and processes using living organisms, cells or enzymes. 2) Autonomously replicating circular, extra-chromosomal bacterial DNA used in gene manipulation. 3) Restriction enzymes. 4) Restriction endonucleases always cut DNA at a specific point by recognizing a specific sequences of base pair known as recognition sequence. 5) DNA ligases 6) The ultimate step in the separation and isolation of DNA fragments through gel electrophoresis in which separated bands of DNAs are cut out from the gel and extracted from the gel piece. 7) Cloning vectors are extra-chromosomal 'replicons' of DNA which can be isolated and can replicate independently of the chromosome. DNA of interest can be cloned into the vector and replicated in host cells 8) ORI point 9) Agrobacterium tumefaciens 10) Microinjection,biolistics(gene gun) 11) Polymerase Chain Reaction 12) Thermusaquaticus 13) Large scale biotechnological product involves the use of bioreactor. 14) Separation and purification 15) Eukaryotic cells have no restriction enzyme. It is present in prokaryotic cell (like bacteria) where these act as defense mechanism to restrict the growth of bacteriophages. 2-Marks Questions 1) Enlist the core techniques that pave the way for modern biotechnology. 2) What is gene cloning? 3) Mention the three steps involve in genetically modifying an organism. 4) Why do bacteria possesses restriction enzyme? 5) Mention one basic difference between restriction endonucleases and exonucleases. 6) What is a palindromic sequence? Give example. 7) What are sticky ends and blunt ends? 116

118 8) Mention the role of selectable marker in cloning vector. 9) What is insertional inactivation? 10) How can you make a bacterial cell competent to take up foreign DNA? 11) Why is Agrobacterium-mediated genetic transformation described as natural genetic engineering in plants? 12) Explain the contribution of Thermus aquaticus in the amplification of a gene of interest. 13) how do you visualize DNA on an agarose gel? HINTS: 1) ( a) Genetic engineering (b) maintenance of sterile ambience. 2) The process of cloning multiple copies of a gene. 3) (a) identification of DNA with desirable genes (b) introduction of the identified DNA into the host and (c) maintenance of introduced DNA in the host and transfer of DNA to its progeny. 4) By restriction enzyme bacteria can attack and destroy the phage DNA in case of viral attack and thereby prevent viral attack. 5) Exonucleases digest DNA from the flank ( beginning/end) of the DNA strands. Whereas endonucleases catalyses the hydrolytic cleavage of DNA in the middle. 6) A segment of double-stranded DNA in which the nucleotide sequence of one strand reads same in reverse order to that of the complementary strand. (always read from the same direction) 7) Double stranded ends of a DNA molecule (without any overhangings) produced by the action of certain restriction enzymes.-[blunt ends)/ Sticky ends - Double stranded ends] of a DNA molecule (with overhangings) produced by the action of certain restriction enzymes 8) The selectable marker genes in a cloning vector allow for the selection and identification of bacteria that have been transformed with a recombinant plasmid compared to nontransformed cells. Some of the most common selectable markers are genes for ampicillin resistance (ampr) and tetracycline resistance (tetr ) and the lacz gene used for blue white selection. 9) Insertional inactivation refers to the loss of activity of the selectable marker genes due to the insertion of foreign DNA within the coding sequence of the marker gene in transfected bacteria. 10) Calcium chloride treatment. 11) Agrobacterium tumefaciens is a pathogen of several dicot plants which exhibit natural genetic engineering in plants. Reasons: It is able to deliver a piece of DNA called T-DNA to transform normal plant cell into a tumour cell. The DNA transforms the normal cells into tumour cells which direct them to produce the chemical essential for the pathogen. 12) Thermus aquaticus produces a thermostable DNA polymerase enzyme which remains active during the high temperature induced denaturation and separation of the double stranded DNA during PCR. 13) a compound called ethidium bromide stains DNA, which on irradiating with ultraviolet fluoresces and gives orange light. Hence, DNA fragments appear as orange band in the presence of ethidium bromide and UV. 3-Marks Questions: 1) Enlist the major steps in recombinant DNA technology. 2) Mention the steps involved in the separation and isolation of DNA fragments through agarose gel electrophoresis. 3) Describe in brief the principle of DNA isolation through gel electrophoresis. 4) Highlight the salient features that are required to facilitate cloning into a vector. 5) Enumerate the major steps for isolation of DNA. 6) Draw a neat,labeled diagram of (a) simple stirred tank bioreactor/ (b) sparged tank bioreactor. 7) What do you mean by replica plating? 8) What are the uses of embryonic stem cells? Answers: 1) R-DNA Technology: 117

119 Restriction enzyme cuts double stranded DNA at its particular recognition sequence. The cuts produce DNA fragments with cohesive ends DNA from a plasmid was also cut by the same restriction enzyme When two of the above mentioned DNA come together they can join by base pairing. DNA ligase enzyme used to unite the backbones of the two DNA fragments, producing R-DNA 2) Agarose gel electrophoresis: 3) DNA When charged molecules are placed in an electric field, they migrate toward either the positive or negative pole according to their charge. In contrast to proteins, which can have either a net positive or net negative charge, nucleic acids have a consistent negative charge imparted by their phosphate backbone, and migrate toward the anode DNA is electrophoresed through the agarose gel from the cathode (negative) to the anode (positive) when a voltage is applied, due to the net negative charge carried on DNA 4) Salient features of a DNA cloning Vectors: Size: small enough to be easily separated from the chromosomal DNA of the host bacteria. Ori site; must have the site for DNA replication that allows the plasmid to replicate separately from the host cell s chromosome. Multiple Cloning sites: a stretch of DNA with recognition sequence for many different commonb restriction enzymes. Selectable marker genes RNApolymerase promoter sequence 5) Major steps for isolation of DNA: Cell containing DNA is treated with lysozyme/cellulose/chitinase DNA along with RNA, Protein, lipid are released Treatment with RNAase, protease to remove RNA and Protein Appropriate treatment to remove other impurities Addition of chilled ethanol to get precipitation of purified DNA 6) Consult NCERT Textbook page number 204 7) In molecular biology and microbiology, replica plating is a technique in which one or more secondary Petri plates containing different solid (agar-based) selective growth media (lacking nutrients or containing chemical growth inhibitors such as antibiotics) are inoculated with the same colonies of microorganisms from a primary plate (or master dish), reproducing the original spatial pattern of colonies. The technique involves pressing a velveteen-covered disk, and then imprinting secondary plates with cells in colonies removed from the original plate by the material. Generally, large numbers of colonies (roughly ) are replica plated due to the difficulty in streaking each out individually onto a separate plate. 8) Embryonic stem cells are pluripotent and depending upon the type of stimulus given, these cells can differentiate into about 200 different cell types present in the body of an adult human being. Thus ES have tremendous potential for use in regenerative medicine to generate organs and tissues for replacement of damaged or diseased ones in case of: Leukemia or cancerous blood cells. Heart diseases, cardiac tissue damage. Paralysis (spinal cord injury) Alzheimer s, Parkinson s, Huntington s disease. Burns (damaged skin cells) 5-Marks Questions: 1) What do you mean by PCR? Briefly enumerate the major steps of PCR. Mention the utility of PCR. Ans: PCR is a cycle of three steps: DENATURATION - the strands of the DNA are melted apart by heating to 95 C. 118

120 ANNEALING - the temperature is reduced to ~ 55 C to allow the primers to anneal to the target DNA. POLYMERISATION/EXTENSION - the temperature is changed to the optimum temperature in order for the DNA polymerase to catalyse extension of the primers, i.e. to copy the DNA between the primers. The cycle is repeated over and over again - as many times as needed to produce a detectable amount of product (DNA). 2) What are the problems of using prokaryotic host like E.coli for production of eukaryotic proteins? Ans: When a eukaryotic gene is expressed in prokaryotic host, there are some problems to be tackled. The foreign gene should ideally be linked to a strong eukaryotic promoter. Otherwise there will not be sufficient expression of eularyotic protein in a prokaryotic system. The non-coding regions or the introns of eukaryotic gene must be excised. This requires use of reverse transcription of mrna into cdna. Additionally, the recombinant protein may not be secreted into the medium or its incorrect folding and accumulation intracellularly may generate inclusion bodies. 119

121 Chapter-12 BIOTECHNOLOGY & ITS APPLICATION Biotechnology is making Genetically modified organisms-microbes, plants, animals for industrial production of Bio-Pharmaceuticals and other useful products. Applications i) Diagnostic & therapeutic ii) Genetically modified crops iii) Waste treatment iv) Energy production v) Food processing vi) Bioremediation Application in agriculture Genetically modified organisms (GMO)-Plants, bacteria, fungi, animals.whose genes are altered by manipulation. Transgenic crops (GMO) -Crops contain or express one or more useful foreign genes. Advantages -i) More tolerant to stresses (heat, cold, draught). ii) Pest resistants GM crops, reduce the use of Chemical pesticides. Eg- BT-Cotton iii) Reduced post harvest losses. Eg- Flavr savr tomato. iv) Enhance nutritional value of food. eg.- Golden Rice (Vitamin A enriched). v) Increased efficiency of mineral use. PEST RESISTANT PLANTS Bt- cotton -- BT stands for Bacillus thuringiensis (Soil Bacteria). Bacterium produces proteins (Crystal Protein-cry I AC, cry II AB). A crystalliane insecticidal protein that kills the insects.hence cry-genes have been introduced in plants to produce crystal proteins as Protoxin (inactive toxin), which is converted to toxins in alkaline medium (i.e. in the gut of insects) and cause death of the insect larva. Protection of plants against nematodes Nematode, Meloidogyne incognita infects tobacco plants & reduces yield. Specific genes (DNA) from nematodes introduced into the plants using Agrobacterium tumifecians (soil bacteria). Genes produce sense and antisense complementary RNA. Act as dsrna and initiates RNAi ( RNA interference) and silences the specific mrna. Complementary RNA neutralizes the specific RNA of nematodes by a process called RNA Interference and parasite cannot live in transgenic host. 120

122 In medicine- genetically engineered insulin rdna technology was applied in therapeutic application by generating genetically engineered insulin for man. In 1983, Eli Lilly, an American company prepared 2 DNA sequences coding for chains A & B. Human insulin consists of two short Polypeptide chains A & B being linked by disulphide bridges.in man, Insulin secreted as Prohormone containing C peptides that is removed during maturation. In rdna technique, insulin could be generated by preparing two separate DNA sequences of A & B chain which are incorporated into plasmids of E. coli to produce insulin chains. Gene therapy Gene therapy involves correction of the gene defects in child or embryo. Adenosine deaminase deficiency is a kind of immuno-disorder caused by deletion of gene coding for ADA. It can be cured by bone marrow transplantation or enzyme replacement therapy. A functional ADA-cDNA(through Retrovirus) is introduced in lymphocyte culture for genetic infusion and transfered to the patient body for normal functioning. Molecular diagnosis -- Early & accurate detection of diseases substituting conventional diagnostic tecniques may be done by following methods: PCR (Polymerase chain reaction): Short stretches of pathogenic genome is amplified for detection of suspected AIDS, Cancer or genetic disorder. 121

123 ELISA (Enzyme Linked Immunosorbent Assay) used to detect AIDS based on detection of antibodies produced against antigen of pathogen. Transgenic Animals Animals with manipulated genes or a foreign gene to be expressed are called as transgenic animals. They are useful- 1. To know how genes contribute to development of disease. 2. To use proteins for treatment of disease. 3. To verify vaccine and chemical safety. LIST OF TRANSGENIC PLANTS & ITS USES Sl. Transgenic plants Application No. 01. Bt Cotton Pest resistant(cotton bollworm), Herbicide tolerant, High yield 02. Flavr Savr Tomato Improved nutrient quality(increased solid nutrient) 03. Potato Increased nutritional quantity(starch content) 04. Brassica napus Hirudin protein prevents blood clotting 05. Golden Rice Enriched in Vitamin-A(B-carotene) 06. Wheat Herbicide resistant 07. Maize Herbicide resistant 08. Corn Insecticide resistant LIST OF TRANSGENIC MICROORGANISMS & ITS USES Sl. No. Transgenic microorganisms Application 01. Bacillus thuringiensis Produces cry protein as plant insecticide 02. Escherichia coli Produces human insulin, interferons,interleukin 03. Pseudomonas fluorescence Prevents frost damage of fruits 04. Pseudomonas putida Scavenging of oil spillage. 05. Rhizobium meliloti Nitrogen fixation by Nif gene 06. Trichoderma Biocontrol of fungal diseases in plants. 07. Tramates Removal of lignin from wood pulp. Biropiracy -- Some organizations and multinational companies exploit or patent bioresources of other nations without proper authorization. Indian patent bill is there to prevent such unauthorized exploitation. GEAC- For validity of GM research and the safety of introducing GM organism. Patent A set of exclusive rights granted by a state (national government) to an inventors or their assignee for a limited period of time in exchange for a public disclosure of an invention. Patents are supposed to satisfy three criteria of : Novelty, non-obviousness, and Utility. 122

124 Novelty implies that the innovation must be new. It cannot be part of prior art or existing knowledge. Non-obviousness implies that it may not be documented but is otherwise well known. The discored fact or product should be of a particular use for the human beings. Controversies in India regarding patent and biopiracy Turmeric: In May, 1995 the US Patent Office granted to the University of Mississippi Medical Center a patent for Use of Turmeric in Wound Healing. Consider the implication of turmeric patent. If an Indian in America sprinkles turmeric powder just as her ancestors in India have done for centuries on her child s scrape, she would in fact be infringing US patent laws and would be open to prosecution. Dr. R A Mashelkar, an Indian scientist is awaken India to Intellectual property Rights issues results The patent was revoked. Neem: In 1996, Vandana Shiva challenged the patent ranted to the firm of W.R. Grace & Co. by the European Patent Office, Munich for fungicidal uses of neem oil. Vandana Shiva and Ajay phadke, who had researched neem in India, flagged ancient Indian texts to point out that there was on novelty factor in neem s magical properties, finally it was overturned in Basmati Rice: In September 1997, a Texas company called Rice Tec won a patent on basmati rice lines and grains. The patent secured lines of basmati and basmati-like rice and ways of selecting that rice for breeding. Rice Tec, owned by Prince Hans-Adam of Liechtenstein, international outrage over allegations of biopiracy. It has also caused a brief diplomatic crisis between India and United States with India threatening to take the matter to WTO ( World Trade Organization) as a violation of TRIPS (trade - related aspects of intellectual property rights) which could have resulted in a major embarrassment for the United States. Both voluntarily, and due to review decisions by the United States patent Office, Rice Tec lost most of the claims of the patent. Three mark question 1) What is the main advantage of producing genetically engineered insulin? Ans- i) Produces only A&B peptides ii) No C-Peptides produced iii)no need to remove C-Peptides during maturation. 2) What are the advantages of Molecular diagnosis technique? Ans- i) Accurate ii) disease can be detected at very early stage iii)can be diagnosed even if the number of pathogens is very low. 3)What are the potential risks ( Three ) of using GM food? Ans Potential risks- i) Products of transgene - allergic or toxic ii) Cause damage to natural environment iii) Weeds also become resistant iv) Can endanger native species 123

125 4)What is hirudin? How do you get it? Ans- Anti coagulant obtained from transgenic Brassica napus. 5) How does agro bacterium help to increase Tobacco production? Ans i) Introduction of Nematode specific gene.ii)production of dsrna(sense and anti-sense) iii)silence specific mrna. 6) Why do farmers face the problems in Agro chemical based farming? Ans i) Too expensive ii) Conventional breeding procedure do not ensure increased production. 7) Why should farmers in India cultivate GM crops? Ans - Tolerant to stress,pest resistant,less post-harvest losses, increased mineral use efficiency. Five mark question 1)Explain the steps involved in the production of genetically engineered insulin? Ans- i) Human insulin consists of 51 amino acids arranged in chains of A and B bearing 21 and 30 a. a respectively interconnected by disulphide bridges. Diagram- Maturation of proinsulin into insulin after removal of c- peptide ii) Insulin synthesized as prohormone has extra c -peptide which is removed during maturation. iii) In 1983, Eli Lilly, American company prepared two DNA sequences similar to A and B chains of human insulin(humulin). iv) Chain A and B extracted and combined by creating disulphide bonds. (HOTS) CHAPTER 12: 1.Name the disease in plants caused by Ti Plasmid? Crown gall disease. 2. What is the main objective of Gene therapy in biotechnological techniques? Gene therapy involves replacement of defective genes by normal genes. 3.Which organism is considered as Natural genetic engineer? Agrobacterium tumefaciens. 4.Which kind of bioweapon is most widely used? 124

126 Bacillus anthracis. 5.What is the main objective of herbicide resistant GM crop? It effectively eliminates the weeds without involving manual labour. 6. From which species is human insulin commercially produced? Escherichia coli 7.Gene medicine refers to use of gene manipulation technology to ameliorate or even permanently cure diseases in human. Name the technique. Gene therapy 8.The bacterium Bacillus thuringiensis provides the major source of insect resistant gene-clarify. Produces insecticidal protein i.e. cry protein that kills certain insect pests. The gene encoding for cry protein is isolated from bacteria & incorporated in major crop plants as biopesticides. 9. 'RNAsilencing is a form of genomic defense. Elucidate the statement taking M. incognitia as an example. RNA-interference technique is adopted to prevent infestation of nematode M. incognitia in the roots of Tobacco plants.nematode specific genes introduced into host plants by complementary ds RNA developed through transposons. 10. Identify a, b, c from the table given below: Nematode specific gene+agrobacterium a Host plant with nematode gene ds DNA c b a) sense RNA b) Anti sense RNA c)silencing mrna 125

127 Chapter 13 ORGANISMS AND POPULATIONS Inter relationship between components of ecosystem Incident solar radiation (100%) 50% lost due to 50% is PAR Photo synthetically Active Radiation Absorption by gases & water vapour Reflected by clouds Scattered by dust particles Loss as heat And light 1-5% Gross primary productivity Respiratory Loss 0.2-1% Net Primary Productivity 0.8-4% Producer Decomposition Primary consumer Death Detritus Secondary consumer Tertiary consumer Fragmentation Leaching Catabolism Humification Mineralization Bio geo chemical cycle 126

128 Ecology It deals with the interaction Among organisms Between organisms & Physical environment. Atmosph Organis Organis Hydrosp Lithosph Biome Biome: the largest ecological regions distinguishable by characteristic plants and animals. There are six: tundra, conifer, deciduous forest, grassland, tropical, and desert. Biomes are subdivided into associations made up of societies. Environment simply means the surrounding Environment Abiotic factors Temperature, soil, water, light Temperature Average temperature varies seasonally Organisms may be Eurythermal or Stenothermal Biotic factors Microorganisms, plants, Animals Eurythermal- wide range of temperature tolerance Stenothermal-Narrow range of temperature tolerance Water Influences life of organisms. No life without water. Productivity and distribution of plants are water dependent. Organisms may be Euryhaline or Stenohaline. Euryhaline- Wide range of salinity tolerence Stenohaline- Narrow range of salinity tolerance. Light Photosynthesis and release of oxygen light dependent. Sciophytes need to use diurnal and seasonal light intensity of forage, migration and reproduction. Soil Nature and proportion of soil in a place depends on climate, weathering process and types of soil. Soil composition, grain size and aggregation determine percolation and water holding capacity of 127

129 soil. Physical and chemical properties determine type of plants and Animals that survive in a habitat. Graph showing abundance of species - low and high limits of abiotic factor e.g. temperature or salinity etc. Response to environmental condition Regulation Suspension Organism Conformation Migration Adaptation Regulation Organisms maintain homeostasis achieved by physiological and behavioral means Thermo regulation and osmoregulation. Conformation # Cannot maintain constant internal Environment # Body temperature and osmotic concentration of body changes with ambient temperature and concentration of medium.-thermo confirmer and osmo confirmer. Migration 128

130 # Organism moves away temporarily to another habitat in stressful condition. e.g.- Migratory birds like Siberian crane Suspension # Organisms suspend their metabolic activities during stressful condition # Resume their function at the return of favorable conditions. E.g. Hibernation (winter sleep) of Frog, Reptiles, Polar Bear etc # Aestivation (summer sleep) in Snail and Fish. Adaptation Morphological, physiological and behavioral changes that enable organisms to adjust to the ever changing environment. E.g. Kangaroo rat survives in desert conditions through internal oxidation of fat, removing concentrated urine of limited quantity. # Allen s rule-cold climate mammals have shorter ears and limbs to minimize heat loss. # Polar mammals like seals have blubber to prevent heat loss. # Burrowing habit to escape from heat # Higher count of RBC, Hb(haemoglobin) at high altitudes. Population attributes *Birth Rate Number of individuals born per thousand per year. *Death Rate Number of individuals die per thousand per year. *Sex Ratio Ratio of male-female in the population. Population density. - the number of individual organisms per unit area (appropriate measure total numbersometimes difficult to determine or meaningless because 4 factors N+I-M+E are concerned w.r.t habitat concerned Age pyramids # Three ecological ages: # Pre-reproductive, Reproductive and Post-Reproductive 129

131 # High proportion pre-reproductive individuals occur in Expanding population # Pre-reproductive individuals are uniform in Stable population. # Pre-reproductive individuals are less in Declining population. Post-Reproductive Representation of age pyramids for human population Reproductive Pre-Reproductive DECLINING EXPANDING STABLE Population growth Factors that affect the size of population Food availability, Weather, Predation pressure, Competition Density of population at any time at a given place depends on Natality, Mortality, Emigration Immigration Population growth models Factors that affect population density The characteristics of populations are shaped by the interactions between individuals and their environment Populations have size and geographical boundaries. The Density of a population is measured as the number of individuals per unit area. The Dispersion of a population is the pattern of spacing among individuals within the geographic boundaries. MEASURING DENSITY Density Number of individuals per unit of area. Population will grow if B+I > D+E Population will shrink if B+I < D+E Population will be in equilibrium if B+I=D+E (1) Population (a) A population in an ecological sense is a group of organisms, of the same species, which roughly occupy the same geographical area at the same time 130

132 (2) Population size (a) A population's size depends on how the population is defined (b) If a population is defined in terms of some degree of reproductive isolation, then that population's size is the size of its gene pool (c) If a population is defined in terms of some geographical range, then that population's size is the number of individuals living in the defined area (3) Population density (a) Given that a population is defined in terms of some natural or arbitrarily defined geographical range, then population density may be defined as simply the number of individual organisms per unit area (b) (4) Patterns of dispersion (a) Individual members of populations may be distributed over a geographical area in a number of different ways including (i) Clumped distribution (attraction) (ii) Uniform distribution (repulsion) (iii) Random distribution (minimal interaction/influence) Types of population interactions INTERACTION SPECIES a SPECIES b Mutualism + + Predation + - Parasitism + - Commensalism + 0 Competition - - Ammensalism - 0 Mutualism Both species benefited. Lichens Relationship between Non-photosynthetic Fungi and photosynthetic Algae or Cyanobacteria. Mycorrhiza Asociation between Fungi and Higher Plants like Pinus. Plants and insects for pollination Orchid ophrys and male bee a good example for co-evolution of plants and animals. 131

133 PREDATION :One species gets benefited and the other harmed. Tiger and Deer Snake and Frog Herbivores and plants Competition : Both the species are harmed. Flammingoes and resident fishes compete for the common food zooplankton in South American lakes. Abington Tortoise and goats in Galapagos Islands for food. Gause s Competitive Exclusion Principle -Two closely related species competing for the same resource cannot co-exist indefinitely and the competitively inferior one will be eventually eliminated. Parasitism One species gets benefit and the other is harmed. Parasites Endoparasites Ectoparasites Brood parasites Liver fluke, Plasmodium lice, ticks Koel Adaptations of parasites # Loss of sense organs # Presence of adhesive organs or suckers # Loss of digestive system # High reproductive capacity. Ammensalism * One species hurts the other but the other is not affected. * Penicillium secretes Penicillin and kill Bacteria but by this Penicillium does not benefit. * Algal bloom leads to death of fishes, but the death of fishes is of no use to the algal bloom. Commensalism * One species benefits and the other neither harmed nor benefited. * The cattle egret catches the insects disturbed by moving cattle, but the cattle neither harmed nor benefited. Another example Clown fish gets protection from predators by close association with sea anemone, but the sea anemone is not effected. Short questions HOTS 1. Why is temperature considered to be the most relevant abiotic factor that influences life of organisms? - Because it affects the enzyme activity. 2. During global warming which type of organism can cope up better Eurythermal or stenothermal? Why? 132

134 - Eurythermal as it can tolerate wide range of temperature. 3. Why does the logistic growth curve becomes S shaped? - Sigmoid curve, population becomes stable due to environmental resistance. Short answer type questions (3 marks) 1. What is brood parasitism? Give an example. What adaptation has evolved in this phenomenon? Ans. One species lays eggs in the nest of another bird, lets the host incubate them. e.g. Cuckoo lays eggs in the nest of a crow. The Eggs of the parasite resemble the eggs of the host in colour, size. Reduce chances of the host bird detecting the foreign eggs and ejecting them from nest. 2. Name and explain the kind of interaction in the following. Ans. 1. Algae and Fungi in Lichens 2. Head Louse Humans 3. Hermit Crab and Sea Anemone (i) Interaction of mutualism where the two species are equally benefited. Fungus provides protection, helps in absorption of water and minerals, Algae provide food for the Fungus. (ii) This is case of Parasitism where the louse is an ectoparasite. Parasite takes shelter on humans and also derives nutrition. (iii) It is commensalisms where one species is benefited and the other is neither benefited nor affected. Sea Anemone is benefited as it does not have to move to places rich in nutrients, while hermit crab is neither benefited nor harmed. 3. How does Ophrys get pollinated by bees? Ans.1. Sexual deceit. 2. One petal resembles female. 3. Male pseudocoupulates with the flower. 4. Pollen grain transferred from one flower to another. 4. Biomass is a more meaningful measure of population size. Explain with an example. Ans. (i) Population large Total number is not an easily adoptable measure. Counting takes long time or practically impossible (ii) There is no need to know the absolute population size for some investigations. (iii) Number may sometimes be misleading eg. In a given area there are 200Parthenium plants and a single banyan tree. Here biomass size of the banyan tree is much more than those of 200Parthenium plants. 5. Give example of how plant protects themselves from the predators. Ans. (i) Thorns.eg. Rose, babool etc. (ii) Chemicals that can kill the animals. eg.- Calotropis etc. 6. What is interference competition? Define competitive exclusion principles. Ans. (i) Feeding efficiency may be reduced due to interference of another species. eg. Tiger and deer. (ii)two closely related species need same resource can not co-exist indefinitely. (5 Marks) Questions: 1.What are the different types of population growth pattern? Mention their differences. Ans: a. Logistic and Exponential growth b. S Shaped curve, J shaped curve. Limiting Factors, No-limiting Factors 2.With the help of age pyramids explain the nature of a population. Ans: a. Pre-reproductive/ re-productive/ post-reproductive b. increasing population/ stable population/ declining population 133

135 The country has 10 different biogeographic zones and 26 biotic provinces. S.No. Biogeographic zones Biotic provinces 1. Trans-Himalaya Ladakh mountains, Tibetan plateau 2. Himalaya Northwest, West, Central and East Himalayas 3. Desert Thar, Kutch 4. Semi-arid Punjab plains, Gujarat Rajputana 5. Western Ghats Malabar plains, Western Ghats 6. Deccan Peninsula Central highlands, Chotta-Nagpur, Eastern highlands, Central Plateau, Deccan South 7. Gangetic plains Upper and Lower Gangetic plains 8. Coast West and East coast, Lakshadweep 9. North-East Brahmaputra valley, Northeast hills 10. Islands Andaman and Nicobar Source: Wildlife Protected Area Network in India: A Review, Wildlife Institute of India, The exponential model of population describes an idealized population in an unlimited environment We define a change in population size based on the following verbal equation. Change in population = Births during Deaths during size during time interval time interval time interval Using mathematical notation we can express this relationship as follows: If N represents population size, and t represents time, then Nis the change in population size and trepresents the change in time, then: N/t = B-D Where B is the number of births and D is the number of deaths 134

136 We can simplify the equation and use r to represent the difference in per capita birth and death rates. N/t = rn OR dn/dt = rn If B = D then there is zero population growth (ZPG). Under ideal conditions, a population grows rapidly. Exponential population growth is said to be happening Under these conditions, we may assume the maximum growth rate for the population (r max ) to give us the following exponential growth dn/dt = r max N The logistic model of population growth incorporates the concept of carrying capacity Typically, unlimited resources are rare. Population growth is therefore regulated by carrying capacity (K), which is the maximum stable population size a particular environment can support. POPULATION GROWTH RATE LOGISTIC GROWTH RATE Assumes that the rate of population growth slows as the population size approaches carrying capacity, leveling to a constant level. S-shaped curve CARRYING CAPACITY The maximum sustainable population a particular environment can support over a long period of time. Population growth 135

137 (a) The simplest case of population growth is that which occurs when there exists no limitations on growth within the environment (b) In such situations two things occur (i) The population displays its intrinsic rate of increase (ii) The population experiences exponential growth Intrinsic rate of population increase (r max ) (a) (b) (e) (f) Intrinsic rate of population increase is the rate of growth of a population when that population is growing under ideal conditions and without limits, ie.as fast as it possibly can (24) Exponential growth (a) Prof. Ramdeo Mishra is known as father of Ecology in India This rate of growth implies that the difference between the birth rate and death rate experienced by a population is maximized However, a population that is not growing maximally can still experience exponential growth "A population with a higher intrinsic rate of increase will grow faster than one with a lower rate of increase. The value of r max for a population is influenced by life history features, such as age at the beginning of reproduction, the number of young produced, and how well the young survive." Exponential growth simply means that a population's size at a given time is equal to the population's size at an earlier time, times some greater-than-one number (b) For example, if a population increased in size per unit time in the following manner: 1, 2, 4, 8, 16, 32, 64, 128, etc. (b) "It has been difficult to demonstrate a direct relationship between population growth rate and specific life history characteristics. Increasingly, ecologists are recognizing that most populations show a mix of the traditional r-selected and K-selected characteristics; life history evolves in the context of a complex interplay of factors." r K Organism size Energy used to make each individual Unstable environment, density independent Small Variable Low Stable environment, density dependent interactions Large constant High # Offspring produced Many Few Timing of maturation Early Late (with much parental care) Life expectancy Short(i.e. high mortality) Long Lifetime reproductive events Environment One Variable and unpredictable More than one Constant or variable but predictable Chapter-14:ECOSYSTEM 136

138 ECOSYSTEMS The interaction between the living organism and the non-living environment is called ecosystem. ECOSYSTEM STUCTURE AND FUNCTION: Interaction of biotic and abiotic components results in a physical structure that is characteristic of each type of ecosystem. Identification and description of plant and animal species of an ecosystem gives its species composition. Vertical distribution of different species occupying different levels is called stratification. The components of the ecosystem are seen to function as a unit: o Productivity. o Decomposition. o Energy flow and o Nutrient cycle. Description of pond as an ecosystem: o The abiotic components include all dissolved inorganic and organic substances and the rich soil deposit at the bottom of the pond. o The solar input, cycle of temperature, day length, regulates the rater of function of the entire pond. o The producer (autotrophic) includes phytoplankton, some algae and the floating, submerged and marginal plants found in edge of pond. o The consumers are represented by zooplankton, free swimming and bottom dwelling animals. o The decomposers are the fungi, bacteria especially abundant at the bottom of the pond. Basic events (in terms of function) in an ecosystem: o Conversion of inorganic into organic material (photosynthesis) by producers. o Consumption of the autotrophs by heterotrophs. o Decomposition and mineralization of the dead organic matter to release them back for reuse by the autotrophs o There is unidirectional flow of energy towards the higher trophic levels and its dissipation and loss as heat to the environment. PRODUCTIVITY: Primary productivity: o The amount of biomass or organic matter produced per unit area over a time period by plants during photosynthesis. o It is expressed in terms of weight (g-2) or energy (kcal m-2) o The rate of biomass production is called productivity. Gross primary productivity: (GPP) is the rate of production of organic matter during photosynthesis. Net primary productivity: o A considerable amount of energy is utilized by plants in respiration. o Gross primary productivity minus respiration losses (R) is the net primary productivity. o GPP R = NPP. Net primary productivity is the available biomass for the consumption to heterotrophs (herbivore and decomposers. Secondary productivity: is defined as the rate of formation of new organic matter by the consumer. DECOMPOSITION: 137

139 Earthworm is said to be friends of farmer: o Breakdown the complex organic matter. o Loosening of the soil helps in aeration and entry of root. The decomposers break down complex organic matter into inorganic substances like carbon dioxide, water and nutrients, called decomposition. Dead plant remains such as leaves, bark, flowers and dead remains of animals, including fecal matter, constitute thedetritus. The process of decomposition completed in following steps: o Fragmentation : Break down of detritus into smaller particles by detritivore (earthworm). o Leaching: Water soluble inorganic nutrients go down into the soil horizon and get precipitated as unavailable salts. o Catabolism : Bacterial and fungal enzymes degrade detritus into simple inorganic substances. o Humification: Accumulation of dark coloured amorphous substances called humus. Importance of humus: o o o o Highly resistance to microbial action. Undergo decomposition at an extremely slow rate. Being colloidal in nature, it serves as reservoir for nutrients. Mineralization: The humus is further degraded by some microbes and release of inorganic nutrients occur. Factor affects rate of decomposition: Decomposition is largely an oxygen-requiring process. Detritus rich in chitin and lignin has slow rate of decomposition. Detritus rich in nitrogen and water-soluble substance like sugar has faster decomposition. Temperature and soil moisture are most important climatic factor that regulate decomposition Warm and moist environment favor decomposition. Low temperature, dryness and anerobiosis inhibit decomposition. ENERGY FLOW IN ECOSYSTEM: Except for deep sea hydrothermal ecosystem, sun is the only source of energy for all ecosystems on earth. Less than 50% of incident solar radiation is photosynthetically active radiations. (PAR). Plants capture 2-10 % of PAR and used in photosynthesis. All organisms depend on the producers, either directly or indirectly. Energy flow in the ecosystem is unidirectional i.e. energy transferred from producer to consumers. Energy transfer is not absolute, and spontaneous, unless energy is degraded it can not be transfer. When energy transferred from one trophic level to another, lot of energy lost in the form of heat to the environment. Only 10% of energy transferred from one trophic level to other. Food chain: Grazing food chain: it extends from producers through herbivore to carnivore. Detritus food chain: Begins with dead organic matter (detritus) and pass through detritus feeding organism in soil to organisms feeding on detritus-feeders. In aquatic ecosystem GFC is the major conduit for energy flow. 138

140 In terrestrial ecosystems a much larger fraction of energy flows through the detritus food chain than through GFC Different food chains are naturally interconnected e.g. a specific herbivore of one food chain may serve as food of carnivores of other food chains. Such interconnected matrix of food chains is called food web. Trophic level: A group of organism irrespective of their size having same source of energy or similar food habit constitute a trophic level. Standing crop: each trophic level has a certain mass of living material at a particular time called as the standing crop. The standing crop is measured as the mass of living organisms (biomass) or the number in a unit area. The number of trophic levels in a food chain is restricted by 10 % flow of energy, less amount of energy available to the last trophic level. ECOLOGICAL PYRAMID: The base of the pyramid is broad and it narrows down at the apex. The similar shape is obtained when food or energy relationship between organisms at different trophic level. The relationship can be expressed in terms of number, energy or biomass. The base of the pyramid represented by producer and apex is the top consumer; other trophic levels are in between. In most ecosystems, all the pyramids, of number, of energy and biomass are upright. The pyramid of number in a tree ecosystem is inverted. The pyramid of biomass in sea also inverted because the biomass of fishes is far exceeds that of phytoplankton. Pyramid of energy is always upright, can never be inverted, because when energy flows from a particular trophic level to the next, some energy is always lost as heat at each step. Limitations of ecological pyramids: It does not take into account the same species belonging to two or more trophic levels. It assumes a simple food chain, it never exits in nature. It dose not accommodate food web. Saprophytes are not given place in ecological pyramids. ECOLOGICAL SUCCESSION: The gradual and fairly predictable change in the species composition of a given area is called ecological succession. Composition and structure of the community constantly change in response to changing environmental condition. This change is orderly and sequential, parallel with the changes in the physical environment. All the changes lead finally to a community that is in near equilibrium with the environment and that is called climax community. During succession some species colonize and area and their populations become more numerous, whereas populations of other species decline and even disappear. The entire sequences of communities that successively change in a given area are called sere. The individual transitional communities are termed as seral stages. In the successive seral stages there is a change in the diversity of species of organisms, in crease in number of species and total biomass. Primary succession: succession that starts where no living organisms are there- these could be areas where no living organism ever existed may be a bare rock or new water body. 139

141 Secondary succession: succession that starts in areas that somehow, lost all the living organisms that existed there. Primary succession occurs in:- newly cooled lava, bare rock, Newly created pond or reservoir. Secondary succession begins in areas where natural biotic communities have been destroyed such as In abandoned farm lands. Burned or cut forest, land that have been flooded Since some soil or sediment is present, secondary succession is faster than primary succession. Succession in plants: Based on the nature of habitat whether it is water or it is on very dry areas- succession of plants is called hydrarchor xerarch. Hydrarch succession takes place in water areas and the successional series progress from hydric to mesiccondition. Xerarch succession takes place in dry areas and the series progress from xeric to mesic conditions. Both hydrarch and xerarch successions lead to medium water conditions (mesic) neither too dry (xeric) nor too wet (hydric) Xerarch succession: Succession in bare rock: The species that invades bare area are called pioneer species. In primary succession on bare rock the pioneer species is the lichen. Lichen secretes acid to dissolve rock, helping in weathering and soil formation. The little soil, leads to growth of bryophytes (mosses). The mosses speed up the process of soil accumulation by trapping wind-blown particles. Lichen moss carpet provides suitable substratum for the germination of seeds of herbaceous plants. Gradually more soil is accumulated and herbaceous species make way for the invasion of shrubs followed by trees. The climax community is generally dominated by trees. Hydrarch (succession in aquatic environment) In primary succession in water, the pioneer species arephytoplankton. Zooplanktons. Sub merged plant stage. (rooted hydrophytes) Sub merged and free-floating plant stage. Reed-swamp stage. Marsh-meadow stage. Shrub stage Trees The climax again would be the forest All the succession whether taking place in water or on land, proceeds to a similar climax community the mesic. NUTRIENT CYCLING: Organism needs constant supply of nutrients to grow, reproduce, and regulate various body functions. Standing state: the amount nutrients such as carbon, nitrogen, phosphorus, calcium etc. present in soil at any given time. 140

142 Nutrient cycling: The movement of nutrient elements through the various component of an ecosystem is called nutrient cycling. Another name of nutrient cycling is biogeochemical cycle. Nutrient cycles are of two types: o Gaseous cycle o Sedimentary cycle. The reservoir for gaseous type of nutrient cycle (nitrogen, carbon) exists in the atmosphere. The reservoir for sedimentary cycle (sulphur, phosphorus) is Earth s crust. Environmental factors like soil, moisture, ph temperature regulate the rate of release of nutrient into the atmosphere. The function of the reservoir is to meet the deficit which occurs due to imbalance in the rate of influx and efflux. Ecosystem Carbon cycle: Carbon constitutes 49 percent of dry weight of organism. Out of total global carbon: o 71 percent carbon found dissolved in ocean. o About 1 percent in the atmosphere. 4 X kg of carbon is fixed in the biosphere by photosynthesis, annually. Large amount of carbon returned to the atmosphere as CO 2 through respiration of producers and consumers. Decomposers also return CO 2 to reservoir during decomposition process. Some amount of Carbon is lost to sediments and removed from circulation. Burning wood, forest fire, combustion of organic matter, fossil fuel, volcanic activities are additional sources for releasing CO 2 to atmosphere. Influence of human activity on Carbon cycling. Rapid deforestation. Massive burning of fossil fuel for energy and transport Increased the rate of release of CO 2 into the atmosphere. Ecosystem Phosphorus cycle: Phosphorus is a major constituent of biological membranes, nucleic acids and cellular energy transfer system(atp) Animals need phosphorus to make shell, bones and teeth. Reservoir pool of phosphorus is the rock, which contain phosphorus in the form of phosphates. During weathering of rock small amount of phosphates dissolved in soil solution and are absorbed by the roots of the plants. Herbivore and other animals obtain organic form of phosphorus from plants. The waste product and dead organisms are decomposed by phosphate-solubilising bacteria releasing phosphorus. How phosphorus cycle differs from carbon cycle? 141

143 There is no respiratory release of phosphorus into atmosphere. Atmospheric inputs of phosphorus through rainfall are much smaller. Gaseous exchange of phosphorus between organism and environment are negligible. ECOSYSTEM SERVICES: PAR: GAP: NPP: DFC: GFC: The products of ecosystem processes are named as ecosystem services. Healthy forest ecosystems purify air and water. Mitigate droughts and flood. Cycle nutrients. Generates fertile soil. Provide wildlife habitat. Maintain biodiversity. Pollinate crops. Provide storage site for carbon Provides aesthetic, cultural and spiritual values Photosynthetically Active Radiation Gross Primary Productivity Net Primary Productivity Detritus Food Chain Grazing Food chain QUESTIONS [2 MARKS QUESTIONS] Q1.What are decomposers? Write their function. Ans-a)Saprotrophs feed on dead bodies of organisms, b) Decomposition and mineralization. Q2.What is the difference between gaseous and sedimentary cycle? Ans-a) Gaseous-Reservoir in atmosphere,nitrogen cycle b) Sedimentary-Soil,eg-phosphorus. Q3.Why is the length of a food chain in an ecosystem generally limited to 3-4 trophic levels? Ans As 90% energy is lost in the form of heat from one trophic level to another, residual energy decreases drastically within 2-3 trophic levels. Q4.What are the differences between detritus and grazing food chains? Ans-a) Begins with Detritus-dead and decaying organic matter. b) Grazing-Begins with living green plants. Q5.What are the two basic catagories of ecosystem? Give example. Ans-a) Terrestrial-Forest, grassland, desert. b) Aquatic-Pond, lake, sea, ocean Q6.Mention two factors by which productivity is limited in an aquatic ecosystem. Ans-a) Light-decreases with increasing water depth. b) Nutrient Limiting factor in Deep Ocean Q7.What is food chain? Give an example. Ans-a) Food and feeding relation among organisms makes a chain like structure b) Grass Deer Lion Q8.Expand PAR, How much PAR is used in gross primary productivity? Ans.Photosynthetically Active Radiation. 2-10%. [ 3 MARKS QUESTIONS] Q1.Briefly describe the process and products of decomposition. Ans-Breakdown of complex organic matter by decomposers.a)process-i)fragmentation ii)leaching iii)catabolism. Humification and mineralization humification leads to accumulation of dark colour substance called humus. Mineralisation result in release of inorgranic substances. Q2.Give account of factors affecting the rate of decomposition. Ans-a) climatic factor i)temp ii) soil b) chemical quality of detritus. Higher temp and moist condition high rate of decomposition.dry soil, High temp Low rate 142

144 Q3) What are ecological pyramids? Mention its limitations. Ans a) Arrangement of trophic levels from producers to top carnivores forms pyramid like structure 3 types i) Pyramid of number ii) Biomass iii) Energy Limitations i) Assumes simple food chain ii) Single species may operate at two or more trophic levels. Q4 ) Explain carbon cycle with ray diagram. Ans Given in text. Q5.Describe pond as an ecosystem. Ans- Pond has biotic and abiotic components a) Biotic Phytoplankton,Zooplankton, small fishes, large fishes, frogs, snake,etc. b) Abiotic - water, dissolved organic and inorganic substances,sunlight, temp. Phytoplankton (microscopic plants) producers. Zooplankton (microscopic animals) primary consumers.small fishes - secondary consumers.large fishes, frog, snails tertiary consumers. [5 Marks Questions] Q1. Describe the major components of ecosystems. Ans- a) Biotic-i) Producer-green plants. ii) Consumers-primary, secondary,tertiary and decomposers. b) Abiotic-i) Physical and climatic factors-soil, temperature,light, humidity. ii) Chemical factors-inorganic chemical substances (sodium, potassium, nitrogen etc.) organic substances-(humus, protein, fat etc.) Q2. Give an account of energy flow in an ecosystem. Ans- Rate of energy transfer between the organisms of different trophic levels is called energy flow. Energy flow is unidirectional, 10% loss of energy in each trophic levels. 2-10% PAR captured by green plants.energy flow diagram from the text. Q3.What is xerosere? Describe the process of succession on a bare rock. Ans-a) Succession on bare rock. b) Steps in Xerosere i) Lichens-Pioneer Community. ii) Mosses iii) Herbs iv) Shrubs v) Trees-Climax community. 143

145 Chapter-15: BIODIVERSITY AND CONSERVATION Biodiversity is defined as the totality of genes, species and ecosystems of a given region, It is the variety and variability of life form (all animals, plants and microbes on earth) and the ecological complexes in which they occur.the term was first coined by Walter G. Rosen(1985),however the term was popularized by the American sociobiologist Edward Wilson(1988) BIODIVERSITY AND CONSERVATION Biodiversity: the term biodiversity refers to the totality of genes, species, and ecosystems of a region. Types of biodiversity described by Edward Wilson: o Genetic diversity: A single species might show high diversity at the genetic level over its distributional range. Medicinal plant Rauwolfia vomitoria of Himalayan range produces active chemical reserpine shows genetic variation. India has more than different strain of rice varieties of mango. Species diversity: different species of a single animal like frog. Ecological diversity: diversity in the ecosystem level like desert, rain forest, mangroves, coral reef, wetlands, estuaries etc. How many species are there on Earth and How many in India? According to IUCN (2004), 1.5 million of plants and animals are in our biosphere. Robert May places global species diversity at about 7 millions. More than 70 percent of all the species recorded are animals. All plants constitute about 22 percent. Among animals insects constitute 70 percent. India has only 2.4 percent of the world s land area; its share of global species diversity is impressive 8.1 percent. India is considered one of the mega diversity countries of the world. Pattern of Biodiversity: Latitudinal gradients: Species diversity decreases as we move away from the equator towards the pole. Tropic (23.5 o N to 23.5 o S) harbors more species than temperate and pole The largely tropical Amazonian rain forest in South America has the greatest biodiversity on earth: 40,000 species of plants species of fishes of birds. 427 amphibians 378 reptiles More than 1, 25,000 invertebrates. 144

146 Why tropical rain forest has greater biodiversity: Unlike temperate regions subjected to frequent glaciations in the past, tropical latitudes have remained relatively undisturbed for millions of years and thus, had a long evolutionary time for species diversification. Tropical environments. Unlike temperate ones, are less seasonal, relatively more constant and predictable, promotes niche specialization and lead to greater species diversity. There is more solar energy available in the tropics, which contribute to higher productivity. Species area relationship: ALEXANDER VON HUMBOLDT observed within a region species richness increased with increasing explored area but only up to a limit. The relation between species richness and area for a wide variety of taxa turns out to be a rectangular hyperbola. On a logarithmic scale the relationship is a straight line describe by the equation LogS = logc +Z log A Where S= species richness, A = Area, Z = slope of the line (regression coefficient), C = Y- intercept. It has been noted that regardless of the taxonomic group or region the slope of the regression line are amazingly similar. However, for a very large area like the entire continent the slope of the line is steeper. Importance of species diversity to the Ecosystem: Community with more species generally tends to be more stable than those with less species. A stable community should not show too much variation in productivity from year to year; it must be resistant or resilient to occasional disturbances (natural or man-made) Stable community must be resistant to invasion by alien species. David Tillman s long-term field experiment finds that: o Plots with more species showed less year to year variation in biomass o Increased diversity contributed to higher productivity. The rivet popper hypothesis: o In an airplane (ecosystem) all parts are joined together by thousands of rivets (species). o If every passenger starts popping a rivet to take home (species extinct), it may not affect flight safety initially but as more and more rivets are removed the plane becomes dangerously weak. o Further more which rivet is removed may also be critical. o Loss of rivets on the wings (key species) is obviously a more serious threat to flight safety than loss of a few rivets on the seats or windows inside the plane. Loss of Biodiversity: The IUCN Red List (2004) documents the extinction of 784 species. Recent extinction includes: o Dodo (Mauritius). 145

147 o Quake (Africa) o Thylacine (Australia) o Stiller s cow (Russia) o Three subspecies of tiger (Bali, Java, Caspian). Since the origin and diversification of life on earth there were five episodes of mass extinction of species. The sixth mass Extinctions in progress now. How the sixth Extinction is different from the previous five extinctions. The current extinction rate is 100 to 1000 times faster. All others are pre-human period, this one is anthropogenic. Effect of biodiversity loss: Decline in plant production. Lowered resistance to environmental perturbations such as drought. Increased variability in certain ecosystem processes such as plant productivity, water use, and pest and disease cycle. Causes of biodiversity loss: The present loss is all due to human activity (anthropogenic) There are four major causes The Evil Quartet are as follows: Habitat loss and fragmentation: Most important cause driving animals and plants to extinct. The tropical rain forest reduced to 6 % from 14 % of earth land surface. The Amazonian rain forest is called as lungs of the planet is being cut cleared for cultivating soya beans. Degradation of many habitat by pollution is also threatens the loss of diversity. Large areas are broken into figments also the cause of diversity loss. Over-exploitation: When need turns to greed it leads to over-exploitation of natural resources. Many species extinctions in the last 500 years (Stiller s cow, passenger pigeons) were due to overexploitation. Many marine fish populations around the world are over harvested. Alien species invasion: The alien species became invasive and cause decline or extinction of indigenous species. Nile perch introduced into Lake Victoria in east Africa led to extinction of 200 species of cichlid fish in the lake. Parthenium, (carrot grass), Lantana, and water hyacinth (Eichornia) posed a thread to indigenous species. 146

148 African cat fish Clarias gariepinus for aquaculture purposed is posing a threat to indigenous catfishes in our rivers. Co-extinction: When a species becomes extinct, the plant and animal species associated with it an obligatory way also become extinct. Extinction of Host species leads to extinction of the parasite also. Co-evolved plant-pollinator mutualism where extinction of one invariably lead to the extinction of the other. BIODIVERSITY CONSERVATION: Why should we conserve Biodiversity? Reason for conservation biodiversity is grouped into three categories. Narrowly utilitarian. Broadly utilitarian Ethical Narrowly utilitarian: Human derive countless direct economic benefits from nature- Food (cereals, pulses, fruits), firewood, fiber, construction material. Industrial products (tannins, lubricants, dyes, resins, perfumes) Products of medicinal importance. Bioprospecting: exploring molecular genetic and species-level diversity for products of economic importance. Broadly Utilitarian Amazonian forest along produce 20% of oxygen during photosynthesis. Pollinator layer: bees, bumblebees, birds and bat that pollinate the plant without which seed cannot be produced by plants. Aesthetic pleasure we get from the biodiversity. How do we conserve biodiversity? In situ conservation: When we conserve and protect the whole ecosystem, its biodiversity at all level is protected we save the entire forest to save the tiger. This approach is called in situ (on site) conservation. Biodiversity hot spot: regions with very high levels of species richness and high degree of endemism.(species confined to that region and not found anywhere else) Hot spot in biodiversity is also regions of accelerated habitat loss. Out of 34 hot spot in the world, three hot spot located in India: o Western Ghats and Srilanka. o Indo-Burma. o Himalaya. 147

149 Other protected area under in situ conservations are: o 14 biosphere reserve o 90 national park o 448 wild life sanctuary Sacred groves: tract of forest were set aside, and all the trees and wildlife within were venerated and given total protection. Ex situ conservation: threatened animals and plants are taken out from their natural habitat and placed in special setting where they can be protected and given special care. Zoological Park. Botanical garden Wildlife safari. Conservation of gamete by cryopreservation. Genetic strains are preserved in seed bank. Convention on Biodiversity: The earth Summit held in Rio de Jeneiro in 1992 called upon all nations to take appropriate measures for conservation of biodiversity and sustainable utilization of its benefits. World Summit on Sustainable development held in 2002 in Johannesburg, South Africa, 190 countries pledged their commitment to achieve by 2010 a significant reduction in the current rate of biodiversity loss at global, regional and local level. Questions: QUESTIONS VSA (1 MARK) 1. Habitat loss and fragmentation has caused severe damage to a particular type of ecosystem. Name it. 2. What trend is observed in respect of species diversity when we move from equator to poles? 3. Which region is considered as the one with highest biodiversity on earth? What is the name given to such region.forests? 4. Ecologists have discovered that value of lies in range of 0.1 to 0.2 regardless of taxonomic group or region. When will the slope of line steeper in species area relationship? 5. Define cryopreservation. Why is it useful in conserving biodiversity? 6. What is the reason for genetic variation shown by medicinal plant Rauwolfia vomitoria? 7. How many species of plants and animals have been described by IUCN in 2004? What is global species diversity according to Robert May? 8. Explain co-extinction with a suitable example. ANSWERS VSA (1 MARK) 1. Tropical Rain Forest. 2. In general, species diversity decreases as we move away from the equator towards poles. 3. Amazonian rain forests. They are also called the Lungs of the planet. 148

150 4. Slope of line is much steeper if one analyses the species Varea relationship among very large areas like entire continents. 5. Preserving a material in liquid nitrogen at 196 C. It can be done to preserve threatened species in viable and fertile condition for long period. 6. Genetic variation might be in terms of potency and concentration of the active chemical reserpine produced by plant. Q1. Define Biodiversity. Ans-totality of genes, species and ecosystems of a given region Q2.What is ecosystem diversity? Ans.-No. of habitats or ecosystem in a given region of the biosphere. Q3.Expand the term IUCN. Ans. International Union for Conservation of Nature and Natural resources. Q4.Who popularized the term biodiversity? Ans.Edward Wilson Q5.Can you mention the estimated number of species so far identified on earth? Ans 1.7 to1.8 million Q6. Establish the relationship between species richness and explored area Ans-.(comment on the species area relationship curve). Q7. Plots with more species showed less year to year variation in total biomass -who showed this? Ans- (David Tilman) Q8.Who proposed the Rivet popper hypothesis? Comment on the major postulate of this hypothesis. Ans- (Paul Ehrlich) Q9.Mention the major causes behind biodiversity loss. Ans-refer study material Q10. Why should we conserve biodiversity? Ans- (comment on the broad/narrow utilitarian and ethical value of biodiversity) Q11.What do you mean by the term ecosystem services? Ans- refer NCERT Text book Q12. What is meant by the term endemism? Ans-native Q13.What are hot spots? Name two factors for declaring a hot spot. What are the hot spots found in India? Ans- Eastern Himalaya and Western Ghat Q14. Distinguish between in-situ and ex-situ conservation measures with examples. Ans- refer concept map Q15.Can you mention some national and international efforts towards biodiversity conservation? Q16. Write short notes on i) sacred groves and ii) traditional ecological knowledge. Ans- refer NCERT text book 149

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152 Chapter 16: Environmental Issues Pollution: Any undesirable change in physical, chemical or biological characteristics of air, land, water or soil which harms the human beings. POLLUTION Water Pollution Misc. Pollution Air Pollution Solid Wastes: Domestic & Industrial wastes. E-Wastes: Electronic garbage, (Wornout Computer, mobiles, refrigerator, etc.) Radioactive Wastes: Utilized radioactive fuels Causes: Industries, Vehicles, Volcanic Erruption, and Household. Pollutants: Metallic & Dust particles, Aerosols, Gases (CO, SO2, NO2) Effects: Harms health of livings(asthma, Bronchitis);Global Warming; Premature death of plants. Water Act (Prevention &Control) Noise Pollution Causes: Domestic Sewage, Agricultural waste (Insecticide & Pesticide), Industrial Waste (PCBP, Heavy metals- Pb, Cd, & Hg) Causes: Vehicles, Industries, Loud speaker, Jet planes. Control: Electrostatic Precipitator, Scruber, Catalytic converter & Fuel Policy Air Act was ammended in 1987 which included noise pollution. Effects: Harms health of livings(diarrhoea, Naru);Retarded growth of plants. Control: Sewage treatment, Awareness among peoples, Proper utilisation of Media. Air Act (Prevention & Control) Effects: Sleeplessness, Increased heart beat, Stress & Anxiety. Permanant hearing loss (150dB) Control: Controlled utilisation of sound producing instruments AIR POLLUTION WATER POLLUTION SOIL POLLUTION NOISE POLLUTION POLLUTION 151

153 Pollutants: Agents that bring about pollution eg. smoke, dust, pollen, chemical pollutants, wastes from hospitals, E-wastes etc. Biodegradable and non -biodegradable pollutants ENVIRONMENTAL ISSUES Pollution: is any undesirable changed in physical chemical or biological characteristics of air, land, water or soil. Pollutant: Any solid, liquid or gas released into the environment in such a huge quantities that make our environment unhealthy is called pollutant. Environment (protection) Act, 1986 to protect and improve the quality of our environment (air, water and soil) AIR POLLUTION AND ITS CONTROL: Effect of air pollution: Cause injury to all living organisms. Reduce growth and yield of crops. Cause premature death of plants. Affects the respiratory system of human being. Particulate size 2.5 micrometers or less are responsible for breathing and respiratory symptoms like irritation, inflammations and damage to the lungs and premature death. Pollution caused by thermal power plant: Sources of particulate matter: thermal power plant, smelters These plants release particulate matter and gaseous air pollutant. A harmless gas released by these plants is Nitrogen and Oxygen. Prevention of air pollution: ways to remove particulate matter: Electrostatic precipitator o Widely used to remove particulate matter in the exhaust from a thermal power plant. o Electrode wires that are maintained at several thousand volts, which produce a corona that release electrons. o Electron binds with particulate matter giving them a net negative charge. o Positively charged collecting plates attract the charged dust particle. Scrubber: o Removes gases like sulphur dioxide. o The exhaust is passed through a spray of water or lime. Methods to reduce vehicular pollution: o Use of lead free petrol or diesel can reduce vehicular pollution. o Catalytic converter: Having expensive metals namely platinum, palladium and rhodium as the catalyst. These metals reduce emission of poisonous gases. The unburnt hydrocarbons are converted into CO 2 and H 2 O. Carbon monoxide and nitric oxide are changed to carbon dioxide and nitrogen gas respectively. Motor vehicle equipped with catalytic converter should use unleaded petrol because lead in the petrolinactivates the catalyst. 152

154 Controlling Vehicular pollution: A case study of Delhi: Use of CNG (compressed natural gas): Advantages of CNG CNG burns most efficiently. Very little remain unburnt. Cannot be siphoned Cannot be adulterated like petrol or diesel. CNG is cheaper than petrol and diesel. Problem of use of CNG: Difficulty in laying down pipelines to deliver CNG Non-assurance of uninterrupted supply. Other parallel steps taken in Delhi: Phasing out old vehicles. Use of unleaded petrol. Use of low-sulphur petrol and diesel. Use of catalytic converter in vehicle. Application of strict pollution level norms for vehicle. New auto fuel policy to cut down vehicular pollution. Steadily reducing the sulphur and aromatic content in petrol and diesel fuels. Euro-II norms o Sulphur reduced to 350 ppm in diesel. o Sulphur reduced to 150 ppm in petrol o Aromatic hydrocarbon to be reduced to 42 %. o Up gradation of vehicle engines. Due to above steps taken by Delhi Govt. there is substantial fall in CO 2 and SO 2 level between 1997 and NOISE POLLUTION: Undesirable high level of sound is called noise pollution. Harm full effect of noise pollution: Psychological and physiological disorder in humans. High sound level, 150dB or more may damage ear drums. Noise causes sleeplessness Increased heart rate. Altered breathing pattern. Prevention of Noise Pollution: Use of sound absorbent materials or by muffling noise in industries Demarcation of horn free zones around hospitals and schools. Permissible sound levels of crackers, Timings after which Loudspeakers cannot be played WATER POLLUTION AND ITS CONTROL: Domestic sewage and industrial effluents: A mere 0.1 percent impurities make domestic sewage unfit for human use Sewage contains dissolve salts like nitrates, phosphates, and other nutrients, and toxic metal ions and organic compounds. The amount of organic matter in water is estimated by BOD. Biochemical oxygen demand: the amount of Oxygen required oxidizing all organic matter present in one liter of water. 153

155 Changes take place on discharge of sewage into the river. o Micro-organism involved in biodegradation of organic matter in the receiving water body consume a lot of oxygen, hence there is sharp decline in dissolved oxygen downstream from the point of discharge. o Due to low DO there is mortality of fish and other aquatic animals. Presence of large amount of nutrients in water also causes excessive growth of Planktonic (free floating) algae, called algal bloom. o Algal bloom imparts distinct color to water bodies. o Deterioration of water quality and fish mortality. o Some bloom-forming algae are extremely toxic to human and animals. The world s most problematic aquatic weed is water hyacinth (Eichhornia crassipes) called Terror of Bengal. o Introduced to India for their lovely flowers. o Excessive growth causes blocks in waterways. o They grow abundantly in eutrophic water bodies. o Causes imbalance in ecosystem and dynamics of water body. Sewage associated with diseases: o Sewage from home and hospital contain pathogenic microbes. o Discharge of such sewage without proper treatment causes diseases like dysentery, typhoid, jaundice, cholera etc. Toxic heavy metals (defined as elements with density > 5g/cm3), released from:- o Petroleum industry. o Paper manufacturing. o Metal extraction and processing. o Chemical manufacturing industries. Biomagnifications: increase in concentration of the toxicant at successive trophic level is called biological magnification or biomagnifications. o Toxic substance accumulated by an organism cannot be metabolized or excreted. o The accumulated toxic passed to the next trophic level. o This phenomenon is well known for mercury and DDT. Bio magnification of DDT in Aquatic food chain. Eutrophication: The process of nutrient enrichment of water and consequent loss of species diversity is referred to aseutrophication. Natural Eutrophication: o Streams draining into the lake increase nutrients like nitrogen and phosphorus. o Increase in nutrient encourages growth of aquatic organisms. o Over centuries, as silt and organic debris pileup the lake grows shallower and warmer. o Warm-water organisms dominate over that thrive in a cold environment. o Marsh plants take root in the shallows and begin to fill in the original lake basin. 154

156 o Eventually the lake gives way to large masses of floating plants (bog), finally converting into land. Cultural or Accelerated Eutrophication: o Pollutants from man s activities like effluents from the industries and homes can radically accelerate the aging process. This phenomenon is called Cultural oraccelerated Eutrophication. Causes: Sewage and agricultural and industrial wastes. Prime contaminants are nitrates and phosphates. Effects: Unsightly scum and unpleasant odors. Robbing the dissolved oxygen form water. Pollutant inflow kills the fish. Decomposition of dead fish causes further depletion of DO. Finally a lake can literally choke to death. Thermal pollution: Cause: Heated (thermal) waste waters flowing out of electricity-generating units. E.g. thermal power plants. Effects: Thermal wastewater eliminates or reduces the number of organism sensitive to high temperature. Enhance the growth of plants and fish in extremely cold areas but only after causing damage to the indigenous flora and fauna. A case study of integrated waste water treatment: Wastewater including sewage can be treated in an integrated manner, by utilizing a mix of artificial and natural process. It has been done in town of Arcata, in the northern coast of California. The treatment is done in two stages:- o The conventional sedimentation, filtering and chorine treatment are given. o The biologist developed a series of six connected marshes over 60 hectares of marshland. o Appropriate plants, algae, fungi and bacteria were seeded into this area, which neutralize, absorb and assimilate the pollutant o The water flows through the marshes, it get purified naturally. The marshes also constitute a sanctuary, with high level of biodiversity in the form of fishes, animals and birds that now reside there. A citizens group called Friends of the Arcata Marsh (FOAM) is responsible for the upkeep and safeguarding of this project. Ecological sanitation: Ecological sanitation is a sustainable system for handling human excreta, using dry composting toilets. This is a practical, hygienic, efficient and cost-effective solution to human waste disposal. With this composting method human excreta can be recycled into are source (as natural fertilizer). EcoSan toilets are being used in Kerala and Srilanka. SOLID WASTES: 155

157 Solid wastes refer to everything that goes out in trash. Municipal solid wastes are wastes from homes, offices, stores, schools, hospitals etc. It comprises paper, food wastes, plastics, glass, metals rubber, leathers, textiles etc. Open damp of these wastes serve as the breeding ground for rats and flies. Sanitary landfills were adopted as substitute for open-burning dumps. Sanitary landfills: Wastes are dumped in a depression or trench after compaction and covered with dirt everyday. Disadvantages: Shortage of space for huge garbage s. Danger of seepage of chemicals, polluting the ground water resources. Solution to solid wastes: All solid wastes are categorized into thee types: o Bio-degradable. o Recyclable. o Non-biodegradable. All the garbage generated is sorted first. Recyclable material to be separated and send for recycles. Biodegradable wastes can be put into deep pits in the ground and be left for natural breakdown. Only Non-biodegradable wastes are left and required to be disposed. Prevention: The need to reduce our garbage generation should be a prime goal. Reduction in use of plastics and use of eco-friendly packaging. Carrying cloth or other natural fiber carry bags when we go shopping. Refusing polythene bags. Case study of Remedy for Plastic wastes: (Ahmed Khan) Polyblend, a fine powder of recycled modified plastic, was developed by his company. Polyblend is mixed with bitumen that is used to lay roads. It increases the water repelling property of bitumen, and helped to increase road life by a factor of three. The raw material used for polyblend is plastic film waste. Hospital wastes: Hospitals generate hazardous wastes that contain disinfectants and other harmful chemicals, and also pathogenic organisms. The use of incinerators is crucial to disposal of hospital wastes. Electronic wastes (e-wastes): Irreparable computers and other electronic goods are known aselectronic wastes (e-wastes). E- Wastes are buried in landfills or incinerated. Metals like copper, iron, silicon, nickel and gold are recovered during recycling process of e-wastes. Manual recycling process exposes workers to toxic substances present in e-wastes. Recycling is the only solution for the treatment of e-wastes. AGRO-CHEMICAL AND THEIR EFFECTS: Use of inorganic fertilizers and pesticides has increased manifold for enhancing crop production. Pesticides, herbicides, fungicides etc, are being increasingly used. These are toxic to non-target organisms that are important components of the soil ecosystem? Increasing amounts of artificial fertilizers causes eutrophication. Case study of organic farming: (Ramesh Chandra Dagar of Sonipat) 156

158 Integrated organic farming is a cyclical, zero waste procedure, where waste products from one process are cycled in as nutrients for other processes. Maximum utilization of resource and increase the efficiency of production. He includes bee-keeping, diary management, water harvesting, composting and agriculture in a chain of processes, which support each other and allow an extremely economical and sustainable venture. Advantages: There is no need of use of chemical fertilizers for crops Cattle excreta are used as manure. Crop waste used to create compost, which can be used as a natural fertilizer or can be used to generate natural gas for energy need. RADIOACTIVE WASTES: Nuclear energy was hailed as a non-polluting way for generating electricity. Later on it was realized that it has two very serious inherent problem:- o Accidental leakage, as occurred in Three Mile Island and Chernobyl. o Safe disposal of radioactive wastes. Radiation from radioactive waste causes mutation at very high rate. High dose of nuclear radiation is lethal, but lower doses create genetic disorders and also cause cancer. Disposal of nuclear wastes: Storage of nuclear waste, after sufficient pre-treatment, should be done in suitably shielded containers buried within the rocks about 500 m deep below the earth s surface. GREEN HOUSE EFFECT AND GLOBAL WARMING: The term Greenhouse effect has been derived from a phenomenon that occurs in greenhouse. In a greenhouse the glass panel lets the light in, but does not allow heat to escape. Therefore the greenhouse warms up, very much like inside a car that has been parked in the sun for a few hours. The greenhouse effect is a naturally occurring phenomenon that is responsible for heating of Earth s surface and atmosphere. Without greenhouse effect the average temperature at surface of earth would have been a chilly -18 o C rather than the present average of 15 o C. Clouds and gases reflect about one-fourth of the incoming solar radiation and absorb some of it but half of incoming solar radiation falls on Earth s surface heating it, while a small portion is reflected back. Earth s surface re-emits heat in the form of infrared radiation but some part of this does not escape into space because of atmospheric gases (e.g. carbon dioxide, methane etc). The molecule of these gases radiate heat energy and a major part of which again comes to Earth s surface, thus heating it up once again. Carbon dioxide and methane are commonly called as greenhouse gases because they are responsible for greenhouse effect. Increase in the level of greenhouse gases has led to considerable heating of Earth leading to global warming orenhanced green house effect. During the past century, the temperature of Earth has increased by 0.6 o C. Effect of global warming: Deleterious changes in the environment and resulting in odd climatic changes (e.g. El Nino effect). Increased melting of polar ice caps as well as of other places like the Himalayan snow caps. Rise in sea level that can submerge many coastal areas. Control of global warming: Reduce use of fossil fuel. 157

159 Improving efficiency of energy usage. Reducing deforestation. Promoting aforestation programme. Slowing down growth of human population. International initiative to be taken to reduce emission of green house gases. OZONE DEPLETION IN THE STRATOSPHERE: Bad ozone formed in the lower atmosphere (troposphere) that harms plants and animals. There is good ozone also; this ozone is found in the upper part of the atmosphere called stratosphere, and it acts as a shield absorbing ultraviolet radiation from the sun. The thickness of ozone layer is measured in terms of Dobson units (DU) Ozone (O 3 ) gas is continuously formed by the action of UV rays on molecular oxygen, and also degraded into molecular oxygen in the stratosphere. There should be proper balance of formation and degradation of ozone. Ozone depletion: Balance of ozone in stratosphere is disrupted due to enhancement of ozone degradation by chlorofluorocarbons (CFCs). CFCs find wide use as refrigerants. CFCs discharged in the lower part of atmosphere move upward and reach stratosphere. In stratosphere, UV rays acts on CFCs and release active Cl atoms. Cl degrades ozone releasing molecular oxygen. Cl acts as catalysts and not consumed during reaction. Whatever CFCs are added to the stratosphere, they have permanent and continuing affects one Ozone levels. The depletion is marked particularly over the Antarctic region. This has resulted in formation of a large area of thinned ozone layer, commonly called as the ozone hole. Effects of UV rays: UV radiations shorter than UV-B are almost completely absorbed by Earth s atmosphere, if the ozone layer is intact. DNA and proteins of living organisms are damaged by UV rays as they potentially absorb it. The high energy of UV rays breaks the chemical bond in these molecules. UV B damages DNA and mutation may occur. It causes ageing of skin. Damage skin cells and causes skin cancers. In human eye cornea absorb UV B radiation and high dose of UV B causes inflammation of cornea called snow-blindness, cataract etc. Such exposes may damage cornea. Prevention: Montreal Protocol was signed at Montreal (Canada) in 1987 to control emission of ozone depleting substances. Many efforts are being made to reduce emission of ozone depleting substances. DEGRADATION BY IMPROPER RESOURCE UTILIZATION AND MAINTENANCE: Soil erosion The removal of top fertile layer due to human activities Reasons: - Over cultivation Unrestricted grazing Deforestation Poor irrigation practices 158

160 Water logging and soil salinity: Irrigation with proper drainage, leads to water lodging in the soil. Draws salt to the surface of the soil. The salt starts collecting at the roots of the plants. The salt damages the roots and crop productions. Deforestation: Conversion of forested areas to non-forested one. How deforestation does occurs: Slash and burn agriculture/jhum cultivation Farmers cut down the trees of the forest and burn the plant remains. Ash is used as fertilizer and land is used for farming or cattle grazing Later, Land is left uncultivated for several years for replenishment of minerals Effects of deforestation Leads to global warming due to excess carbon-dioxide Loss of biodiversity Damage to hydrological cycle Leads to soil erosion Desertification of land Reforestation Restoring forest that was existing earlier E.g. Observing Van-Mahotsavas It also occurs naturally Aforestation Developing a forest in a new area where no such forest existed in that area. A case study of people s participation in forest conservation A king of Jodhpur wanted to arrange wood for his new palace in Few Bishnois hugged the trees and asked to cut them first rather than cutting trees. 365 persons lost their lives in this act A small temple is now present there in remembrance of this act Amrita Devi Bishnois Wild Life Protection Award is instituted for individuals of rural areas who take keen interest in protecting wild life. Chipko movement It was started by local women of Garhwali; they hugged the trees to protect them from the axes of contractors. Joint forest management (jfm) Strategy Government of India in 1980 Local communities worked with the government to save the forest. Communities get forest products for encouragement. CPCB: Central Pollution Control Board BOD: Biological Oxygen Demand CNG: Compressed Natural Gas FOAM: Friends of Arcata Marsh JFM: Joint Forest Management. Ozone depletion Ozonosphere protects earth from harmful radiation. In stratosphere,photodissociation results in ozone formation that dissipates the energy of UV radiation. O 3 O 2 + O UV CFC produces active chlorine in presence of UV radiation & depletes ozone layer. UV-C CFCl 3 CFCl 2 +Cl 159

161 UV-C CFCl 2 CFCl+Cl Cl+O 3 ClO +O 2 C lo +O 3 Cl +2O 2 Triatomic molecule of oxygen.. Found in stratosphere of atmosphere. CFCs discharged from lower atmosphere move upward. UV rays act on these CFCs and release chlorine atoms. Chlorine degrades ozone and release molecular oxygen. This process is irreversible and thus ozone is depleted. Environmental issues Very short answer type questions (1mark) 1. What is meant by algal blooms? What is its significance? Ans. Excess growth of certain phytoplankton due to excess nutrients in water causes Deteriorates water quality, leads to fish mortality. 2. Define eutrophication. Ans. Nutrient enrichment in water bodies leading to depletion of oxygen and loss of life supporting Environment. 3. What is bio magnification? Ans. Increase in the concentration of certain toxic chemicals at successive trophic levels. 4. What is BOD? Ans. Biological Oxygen Demand is the measure of organic matter in any water sample. 5. What is the effect of DDT in birds? Ans. DDT disturbs calcium metabolism in birds, thinning of egg shell and premature breaking of Eggs lead to decline in bird population. 6. What do you understand by Ecosan? Ans. Ecosanare the toilets which use compositing method for ecological sanitation. 7. Why are nuclear wastes called potent pollutants? Ans.Are lethal even at lower doses and cause damaging disorders. 8. What is Jhum cultivation? Ans Farmers cut down the tress, burn, use cattle for grazing and then allow the land to recover. 9. Mention two problems that have arisen due to green revolution. Ans. Water logging and soil salinity. 10. What is snow blindness? Ans. Inflammation of cornea caused by a high dose of UV-B radiation. 11. Which is the world s most problematic weed, also known as terror of Bengal? Ans. Eichornia crassipes(water hyacinth) What is the effect of DDT in birds? Ans. Disturbs Calcium metabolism Thinning of egg shells and premature breakage of eggs, Decline of bird population. Short answer type questions (2 marks) 1. Mention the harm caused by fine particulate matter to human beings? Ans. (i) Cause respiratory problems (ii) Irritation of eyes (iii) Inflammation of lungs (iv) Premature death. 160

162 2. Differentiate between biodegradable and non-biodegradable wastes. Biodegradable wastes Non-Biodegradable wastes *Can be broken down into harmless simple *Cannot be broken down by microbes and get Compounds by the action of decomposers. accumulated in the biosphere *Can be used as manure *Enter the food chain *Cause little pollution *Cause bio magnifications 3. Describe Chipko Movement. Ans. It was launched in Garwhal, Himalayas by Shri Sunder LalBahuguna in Local women showed enormous bravery in protecting the trees from the axes of the contractors by hugging them. 4. What are the advantages of Organic farming? Ans. Economical procedure as recycling takes place. Waste not accumulated but recycled Efficiency and utilization of resources increased Does not lead to eutrophication. 5. Write an account on Ecological sanitation (Ecosan). Ans.A sustainable system for handling human excreta, using dry composting toilets. Practical, Hygienic, efficient and cost-effective solution to human waste disposal Human excreta can be Recycled into manure Used in Kerala and Sri Lanka. 6. How do radioactive wastes cause damage to living organism? Ans. Cause mutations in living organisms at a very high rate. Lethal in high doses Causes cancer and other disorders.reduces the vegetation cover. 7. What is ecological sanitation? What are its advantages? Ans. It is sustainable system for handling human excreta without using water but by composting Method. Advantages Hygienic, practical and efficient, Conserves water can be recycled and, Acts as a natural fertilizer. Short answer type questions (3 marks) 1. Mention harmful effects of noise pollution on human health. Ans. Stress Altered breathing pattern Increased heart beating and blood pressure Sleeplessness and headache Hearing impairment. 2. What measures should be taken to reduce global warming? Ans. Reduce use of fossil fuel Efficient use of energy. Avoid deforestation Reduce human population Control greenhouse gases. 3. How can we reduce automobile pollution? Ans. Un-Leaded Petrol- Reduces lead pollution in air. Low Sulphur Diesel- Reduces sulphur pollution in air Four stroke engines to reduce emission of unburnt hydrocarbons. Tube-Ups to increase air-fuel ratio and help in better combustion. Catalytic Converters to reduce pollution. CNG to reduce pollution and conserve fossil fuels. 161

163 4. Mention the adverse effects agrochemicals. Ans. They are toxic to non-target organisms. They cause soil pollution Excess fertilizers cause eutrophication. 5. Write a short note on ozone depletion. Ans. Ozone found in stratosphere. CFCs discharged from lower atmosphere move upward. In stratosphere UV rays act on these CFCs release chlorine atoms. Chlorine degrades ozone and release molecular oxygen (O3O2). In this reaction chlorine acts, as catalyst and loss ozone is irreversible. 6. Mention the Supreme Court directions to the Government to reduce pollution. Ans. Switch over to CNG in public transport system Enforcement of Euro II norms for vehicles. Compulsory periodic check-up of pollution. Use of unleaded petrol Low sulphur petrol and diesel Catalytic converters in vehicles Phasing out of old vehicles. Long answer type questions (5marks) 1. a) Explain the functioning of electrostatic precipitator with the help of a diagram. b) Mention the consequence if the electrostatic precipitator does not work in a power plant. Ans. Used for removing particulate air pollutants. Removes about 99 of the particulate pollutants from the exhaust of thermal power plants. Electrode wires that are maintained at several thousand volts, which release electrons. Electrons become attached to dust particles giving a net negative charge. Collecting plates are grounded and attract the charged dust particles. Velocity of air between the plates must be low enough to allow the dust particles to fall. If electrostatic precipitator of a thermal plant stops working, all the particulate pollutants get released and pollute the air. Discharge corona Negatively charged wire Dirty Air Dust particles Clean air Collection plate grounded ELECTROSTATIC PRECIPITATOR IMPORTANT LEGISLATIONS FOR ENVIRONMENTAL PROTECTION Sl. No. Environmental Act Application 01. The Environment Protection Protect & control the quality of environment Act, The Air (Prevention & Protect & control of air pollution 162

164 control) Act, The Water (Prevention & control) Act, 1974 Protect & control of water pollution to safe guard water resources 04. The Insecticide Act, 1968 Control & regulation of safe distribution & use of insecticides 05. Montreal Protocol Control on emission of ozone depleting substances 06. National Forest Policy,1988 Restriction of forest cover for plain land & hills 07. Kyoto Protocol,1977 Reducing overall greenhouse gas emission Photochemical oxidation (SMOG) : Secondary air pollutants are produced from primary pollutants by photochemical oxidation. eg.,olefins, aldehydes, Peroxyacetyl Nitrate(PAN) Photochemical Smogs are formed by following reactions: N 2 + O 2 2NO (From vehicle exhaust) 2NO + O 2 2NO 2 UV NO 2 NO + O O +O 2 O 3 NO +O 3 NO 2 +O 2 HC +NO + O 2 NO 2 +PAN (Peroxyacetyl nitrate)(smog) 163

165 CENTRAL BOARD OF SECONDARY EDUCATION BIOLOGY (044) CLASS XII Time: 3 Hours Max. Marks: 70 Unit Title No of Periods Marks 1 Reproduction Genetics and Evolution Biology and Human welfare Biotechnology and its Applications Ecology and Environment Total Unit 1: Reproduction Reproduction in organisms: Reproduction, a characteristic feature of all organisms for continuation of species; modes of reproduction - asexual and sexual reproduction; asexual reproduction - binary fission, sporulation, budding, gemmule, fragmentation; vegetative propagation in plants. Sexual reproduction in flowering plants: Flower structure; development of male and female gametophytes; pollination - types, agencies and examples; outbreeding devices; pollen-pistil interaction; double fertilization; post fertilization events - development of endosperm and embryo, development of seed and formation of fruit; special modes-apomixis, parthenocarpy, polyembryony; Significance of seed dispersal and fruit formation. Human Reproduction: Male and female reproductive systems; microscopic anatomy of testis and ovary; gametogenesis - spermatogenesis and oogenesis; menstrual cycle; fertilisation, embryo development upto blastocyst formation, implantation; pregnancy and placenta formation (elementary idea); parturition (elementary idea); lactation (elementary idea). Reproductive health: Need for reproductive health and prevention of sexually transmitted diseases (STD); birth control - need and methods, contraception and medical termination of pregnancy(mtp); amniocentesis; infertility and 164

166 assisted reproductive technologies - IVF, ZIFT, GIFT (elementary idea for general awareness). Unit 2: Genetics and Evolution Heredity and variation:mendelian inheritance; deviations from Mendelism - incomplete dominance, co-dominance, multiple alleles and inheritance of blood groups, pleiotropy; elementary idea of polygenic inheritance; chromosome theory of inheritance; chromosomes and genes; Sex determination - in humans, birds and honey bee; linkage and crossing over; sex linked inheritance - haemophilia, colour blindness; Mendelian disorders in humans - thalassemia; chromosomal disorders in humans; Down's syndrome, Turner's and Klinefelter's syndromes. Molecular basis of inheritance: Search for genetic material and DNA as genetic material; Structure of DNA and RNA; DNA packaging; DNA replication; Central dogma; transcription, genetic code, translation; gene expression and regulation - lac operon; genome and human genome project; DNA fingerprinting. Evolution: Origin of life; biological evolution and evidences for biological evolution (paleontology, comparative anatomy, embryology and molecular evidence); Darwin's contribution, modern synthetic theory of evolution; mechanism of evolution - variation (mutation and recombination) and natural selection with examples, types of natural selection; Gene flow and genetic drift; Hardy - Weinberg's principle; adaptive radiation; human evolution. Unit 3: Biology and Human Welfare Health and disease: Pathogens; parasites causing human diseases (malaria, DENGUE, CHICKENGUNIA filariasis, ascariasis, typhoid, pneumonia, common cold, amoebiasis, ring worm); Basic concepts of immunology - vaccines; cancer, HIV and AIDS; Adolescence, drug and alcohol abuse. Improvement in food production: Plant breeding, tissue culture, single cell protein, Biofortification, Apiculature and Animal husbandry. 165

167 Microbes in human welfare: In household food processing, industrial production, sewage treatment, energy generation and as biocontrol agents and biofertilizers. Unit 4: Biotechnology and Its Applications Principles and processes of biotechnology: Genetic Engineering (Recombinant DNA Technology). Application of biotechnology in health and agriculture: Human insulin and vaccine production, gene therapy; genetically modified organisms - Bt crops; transgenic animals; biosafety issues, bio piracy and patents. Unit 5: Ecology and Environment Organisms and environment: Habitat and niche, population and ecological adaptations; population interactions - mutualism, competition, predation, parasitism; population attributes - growth, birth rate and death rate, age distribution. Ecosystems: Patterns, components; productivity and decomposition; energy flow; pyramids of number, biomass, energy; nutrient cycles (carbon and phosphorous); ecological succession; ecological services - carbon fixation, pollination, seed dispersal, oxygen release. Biodiversity and its conservation: Concept of biodiversity; patterns of biodiversity; importance of biodiversity; loss of biodiversity; biodiversity conservation; hotspots, endangered organisms, extinction, Red Data Book, biosphere reserves, national parks and sanctuaries AND RAMSAR SITES. Environmental issues: Air pollution and its control; water pollution and its control; agrochemicals and their effects; solid waste management; radioactive waste management; greenhouse effect and global warming; ozone depletion; deforestation; any three case studies as success stories addressing environmental issues. 166

168 A. List of Experiments 1. Study pollen germination on a slide. 2. Collect and study soil from at least two different sites and study them for texture, moisture content, ph and water holding capacity. Correlate with the kinds of plants found in them. 3. Collect water from two different water bodies around you and study them for ph, clarity and presence of anyliving organism. 4. Study the presence of suspended particulate matter in air at two widely different sites. 5. Study the plant population density by quadrat method. 6. Study the plant population frequency by quadrat method. 7. Prepare a temporary mount of onion root tip to study mitosis. 8. Study the effect of different temperatures and three different ph on the activity of salivary amylase on starch. 9. Isolation of DNA from available plant material such as spinach, green pea seeds, papaya, etc. B. Study/observation of the following (Spotting) 1. Flowers adapted to pollination by different agencies (wind, insect, bird). 2. Pollen germination on stigma through a permanent slide. 3. Identification of stages of gamete development, i.e., T.S. of testis and T.S. of ovary through permanent slides(from grasshopper/mice). 4. Meiosis in onion bud cell or grasshopper testis through permanent slides. 5. T.S. of blastula through permanent slides. 6. Mendelian inheritance using seeds of different colour/sizes of any plant. 7. Prepared pedigree charts of any one of the genetic traits such as rolling of tongue, blood groups, ear lobes, widow's peak and colour blindness. 167

169 8. Controlled pollination - emasculation, tagging and bagging. 9. Common disease causing organisms like Ascaris, Entamoeba, Plasmodium, Roundworm through permanent slides or specimens. Comment on symptoms of disease that they cause. 10. Two plants and two animals (models/virtual images) found in xeric conditions. Comment upon their morphological adaptations. 11. Two plants and two animals (models/virtual images) found in aquatic conditions. Comment upon theirmorphological adaptations. Practical Examination for Visually Impaired Students of Classes XII Evaluation Scheme Time Allowed: Two hours Max. Marks: 30 Identification/Familiarity with the apparatus Written test (Based on given / prescribed practicals) Practical Records Viva Total 5 marks 10 marks 5 marks 10 marks 30 marks General Guidelines The practical examination will be of two hour duration. A separate list of ten experiments is included here. The written examination in practicals for these students will be conducted at the time of practical examination of all other students. The written test will be of 30 minutes duration. The question paper given to the students should be legibly typed. It should contain a total of 15 practical skill based very short answer type questions. A student would be required to answer any 10 questions. A writer may be allowed to such students as per CBSE examination rules. All questions included in the question papers should be related to the listed practicals. Every question should require about two minutes to be answered. These students are also required to maintain a practical file. A student is expected to record at least five of the listed experiments as per the specific instructions for each subject. These practicals should be duly checked and 168

170 signed by the internal examiner. The format of writing any experiment in the practical file should include aim, apparatus required, simple theory, procedure, related practical skills, precautions etc. Questions may be generated jointly by the external/internal examiners and used for assessment. The viva questions may include questions based on basic theory/principle/ concept, apparatus/materials/chemicals required, procedure, precautions, sources of error etc. Class XII A. Items for Identification/ familiarity with the apparatus for assessment in practicals (All experiments) Beaker, flask, petridishes, soil from different sites- sandy, clayey, loamy, small potted plants, aluminium foil, paintbrush, test tubes, starch solution, iodine, ice cubes, Bunsen burner/water bath, large colourful flowers, Maize inflorescence, model of developmental stages highlighting morula and blastula of frog, beads of different shapes (cubes, round) /size, smooth and rough, tags of different shapes, bags, Ascaris, Cacti (opuntia, mammalaria) B. List of Practicals 1. Study of the soil obtained from at least two different sites for their texture and water holding capacity. 2. Study of presence of suspended particulate matter in air at two widely different sites. 3. Study of the effect of different temperatures on the activity of salivary amylase. 4. Study of flowers adapted to pollination by different agencies (wind, insects). 5. Identification of T.S of morula or blastula of frog. 6. Study of Mendelian inheritance pattern using beads of different colour/sizes. 7. Prepararation of pedigree charts of genetic traits such as rolling of tongue, colour blindness. 8. Study of emasculation, tagging and bagging by trying out an exercise on controlled pollination. 9. Identify common disease causing organisms like Ascarisand learn some common symptoms of the disease that they cause. 10. Comment upon the morphological adaptations of plants found in xerophytic conditions. 169

171 Note: The above practicals may be carried out in an experiential manner rather than recording observations. QUESTION WISE BREAK UP Types of Mark(s) per Total No. Total Question(s) Question of Marks VSA 1 5 Questions 05 SA-I SA-II VBQ LA Internal Choice: There is Total no overall choice in the paper. However, there is an internal choice in one question of marks weightage, one question of 3 marks weightage and all three questions of 5 marks weightage. 2. The above template is only a sample. Suitable internal variations may be made for generating similar templates keeping the overall weightage to different form of questions and typology of questions same. 170

172 BIOLOGY CODE (044) QUESTION PAPER DESIGN CLASS XII S. No. Typology of Questions 1 Remembering- (Knowledge based Simplerecall questions, to knowspecific facts, terms,concepts, principles, or theories, Identify, define,or recite, information) 2 Understanding- (Comprehension -to be familiar with meaning andto understandconceptually, interpret, compare, contrast, explain,paraphrase 3 Application (Use abstractinformation in concretesituation, to apply knowledge to newsituations, Use given content to interpret a situation, provide anexample, or solve a problem) 4 High Order Thinking Skills ( Analysis & Very Short Answer (VSA) Short Answer-I (SA-I) (2 marks) Short Answer -II (SA-II) (3 marks) Value based question Long Anser (L.A.) (5 marks) Total Marks % Weightage % % % % Synthesis- Classify, compare, contrast, or differentiate betweendifferent pieces of information, Organizeand/or integrate unique pieces of information 5 Evaluation and Multi % Disciplinary- (Appraise,judge, and/or justify the value or worth of a decisionor outcome, or to predict outcomes based on values) TOTAL 5 x 1= 5 5 x 2= 10 12x3=36 1x4=4 3x5=15 70(26) 100% 171

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DELHI PUBLIC SCHOOL MATHURA ROAD, NEW DELHI FORTNIGHTLY BREAK UP OF THE SYLLABUS. Subject : Biology Class - XII Academic Session :

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