Strictly According to the New Syllabus Prescribed by the Central Board of Secondary Education. A Textbook of CBSE. For Class XiI

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2 Strictly According to the New Syllabus Prescribed by the Central Board of Secondary Education A Textbook of CBSE For Class XiI Sarita Aggarwal M.Sc., B.Ed. Former PGT Modern School, Vasant Vihar New Delhi Former Principal Amity International School Mayur Vihar, Phase-I Delhi With Value Based Questions

3 S. CHAND SCHOOL BOOKS (An imprint of S. Chand Publishing) A Division of S. Chand And Company Pvt. Ltd. (An ISO 9001 : 2008 Company) 7361, Ram Nagar, Qutab Road, New Delhi Phone: , , ; Fax: helpdesk@schandpublishing.com Branches : Ahmedabad : Ph: , , ahmedabad@schandpublishing.com Bengaluru : Ph: , , bangalore@schandpublishing.com Bhopal : Ph: , , bhopal@schandpublishing.com Chandigarh : Ph: , , chandigarh@schandpublishing.com Chennai : Ph , , chennai@schandpublishing.com Coimbatore : Ph: , , coimbatore@schandpublishing.com (Marketing Office) Cuttack : Ph: , , cuttack@schandpublishing.com Dehradun : Ph: , , dehradun@schandpublishing.com Guwahati : Ph: , , guwahati@schandpublishing.com Hyderabad : Ph: , , hyderabad@schandpublishing.com Jaipur : Ph: , , jaipur@schandpublishing.com Jalandhar : Ph: , , jalandhar@schandpublishing.com Kochi : Ph: , , cochin@schandpublishing.com Kolkata : Ph: , , kolkata@schandpublishing.com Lucknow : Ph: , , lucknow@schandpublishing.com Mumbai : Ph: , , mumbai@schandpublishing.com Nagpur : Ph: , , , nagpur@schandpublishing.com Patna : Ph: , , patna@schandpublishing.com Pune : Ph: , pune@schandpublishing.com Raipur : Ph: , raipur@schandpublishing.com (Marketing Office) Ranchi : Ph: , ranchi@schandpublishing.com Siliguri : Ph: , siliguri@schandpublishing.com (Marketing Office) Visakhapatnam : Ph: , visakhapatnam@schandpublishing.com (Marketing Office) 2013, Sarita Aggarwal All rights reserved. No part of this publication may be reproduced or copied in any material form (including photocopying or storing it in any medium in form of graphics, electronic or mechanical means and whether or not transient or incidental to some other use of this publication) without written permission of the publisher. Any breach of this will entail legal action and prosecution without further notice. Jurisdiction : All disputes with respect to this publication shall be subject to the jurisdiction of the Courts, Tribunals and Forums of New Delhi, India only. First Published in 2013 Reprints 2014, 2015 Revised Edition 2016 ISBN : Code : 1003B 418 PRINTED IN INDIA By Vikas Publishing House Pvt. Ltd., Plot 20/4, Site-IV, Industrial Area Sahibabad, Ghaziabad and Published by S. Chand And Company Pvt. Ltd., 7361, Ram Nagar, New Delhi

4 Preface to the First Edition This comprehensive Textbook of CBSE Biology for Class XII has been written strictly in accordance with the latest syllabus prescribed by the Central Board of Secondary Education. Biology is a fascinating study of life. The book explains the essential concepts of biology to the students, linking them to examples in everyday life. Biologists, aided by new researches, have cracked the Human Genome Sequence; fortified crops (like Golden Rice), taken new stem cell initiatives and have been encountering new leaps in the field of tackling human diseases. Thus, this textbook aims to teach biology to the students in such a manner so that they become informed citizens of the 21st century. Some unique features of the book are : Concise and accurate treatment of the subject matter Very simple language within the comprehension of students. Comparative tables to highlight the differences between important terms Profusely illustrated with examples and well labelled diagrams Subject matter (encompassed in the well etched sixteen chapters) is written in such a way that makes the scientific concepts clear and understandable. All the chapters contain new material as per the latest syllabus. At the end of each chapter, Important Points and Key Terms have been given for quick summary of the chapter. According to the latest examination pattern (With Value Based Questions) Variety of Review Questions for self assessment and recapitulation which include: Multiple choice questions, Fill in the blanks, Match the columns, True/False, NCERT Textbook Questions (With solutions) and HOTS (Higher order Thinking Skills) Questions with solutions, Short Answer Type Questions and Long Answer Type Questions. It makes the students confident to tackle the competitive exams as well. Questions from latest Examination Paper (with Answers) We are thankful to the Management Team and the Editorial Department of S. Chand & Company Pvt. Ltd. for all help and support in the publication of this book. Hope this book will meet the aspirations of the students for whom it has largely been written. Suggestions for further improvement, along with constructive criticism, from teachers and students will be gratefully acknowledged. Author ACKNOWLEDGEMENTS The author wishes to express sincere thanks to her husband and daughters Shruti and Samridhi for their constant support and encouragement shown throughout the preparation of this book. She also wishes to extend gratitude to her parents without whose inspiration, this book would not have been possible. Disclaimer : While the author of this book has made every effort to avoid any mistake or omission and has used her skill, expertise and knowledge to the best of her capacity to provide accurate and updated information. The author and S. Chand do not give any representation or warranty with respect to the accuracy or completeness of the contents of this publication and are selling this publication on the condition and understanding that they shall not be made liable in any manner whatsoever. S. Chand and the author expressly disclaim all and any liability/responsibility to any person, whether a purchaser or reader of this publication or not, in respect of anything and everything forming part of the contents of this publication. S. Chand shall not be responsible for any errors, omissions or damages arising out of the use of the information contained in this publication. Further, the appearance of the personal name, location, place and incidence, if any; in the illustrations used herein is purely coincidental and work of imagination. Thus the same should in no manner be termed as defamatory to any individual. (iii)

5 Syllabus Class XII (Theory) One Paper Time : 3 Hours No. of Periods Marks Unit Title 1. Reproduction Genetics and Evolution Biology and Human Welfare Biotechnology and its Applications Ecology and Environment Total I. reproduction (30 Periods) Reproduction in organisms: reproduction, a characteristic feature of all organisms for continuation of species; asexual reproduction modes of reproduction - asexual and sexual reproduction; asexual reproduction - binary fission, sporulation, budding, gemmule, fragmentation; vegetative propagation in plants. Sexual reproduction in flowering plant: flower structure; development of male and female gametophytes; pollination - types, agencies and examples; outbreeding devices; pollenpistil 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 assisted reproductive technologies IVF, ZIFT, GIFT (elementary idea for general awareness). II. Genetics and Evolution (40 Periods) 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 disorder (iv)

6 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 and rice 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. III. Biology and Human Welfare (30 Periods) Health and disease: pathogens; parasites causing human diseases (malaria, dengue, chicken guinea, 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 chicken production : Plant breeding, tissue culture, single cell protein, Biofortification, Apiculture and Animal husbandry. Microbes in human welfare: In household food processing, industrial production, sewage treatment, energy generation and as biocontrol agents and biofertilizers. Antbiotics; production and judicious uses. IV. Biotechnology and Its Applications (30 Periods) Principles and process 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 biopiracy and patents. V. Ecology and Environment (30 Periods) 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 in brief). 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. Environmental issues: Air larger pollution and its control; water pollution and its control; agrochemicals and their effects; solid waste management; radioactive waste management; greenhouse effect and global and climate change; ozone layer depletion; deforestation; any one case study as success story addressing environmental issues. Diseases; dengue and chickengunia. (v)

7 PRACTICAL Maximum Marks : 30 (60 Periods) 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 of soil. 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 any living organisms. 4. Study the presence of suspended particulate matter in air at two widely different sites. 5. Study of plant population density by quadrate method. 6. Study of plant population frequency by quadrate 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. DNA banding in plant tissues. Study/observation of the following (Spotting) 1. Flowers adapted to pollination by different agencies (wind, insect). 2. Pollen germination on stigma through a permanent slide. 3. Identification of stages of gamete development i.e. T.S. testis and T.S. ovary through permanent slides (from any mammal). 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. Study 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. 8. Exercise on controlled pollination - emasculation, tagging and bagging. 9. Identification of common disease causing organisms like Ascaris, Entamoeba, Plasmodium, ringworm through permanent slides or specimens. Comment on symptoms of disease that they cause. 10. Two plants and two animals found in xeric conditions. Comment upon their morphological adaptations. 11. Plants and animals found in aquatic conditions. Comment upon their morphological adaptations. (vi)

8 Contents Unit I Reproduction 0 1. reproduction in Organisms Life Span Reproduction Asexual Reproduction Vegetative Propagation Sexual Reproduction Events in Sexual Reproduction Special Modes of Reproduction Some Deviations in Sexually-Reproducing Animals 30 Important Points 31 Key Terms 32 Review Questions 33 NCERT Textbook Questions with Solutions 35 Higher Order Thinking Skills Questions with Solutions Sexual reproduction in Flowering Plants Flower: A Fascinating Organ of Angiosperms Pre-Fertilisation: Structures and Events Pollination Outbreeding Devices Pollen-pistil Interaction Pollen Germination Artificial Hybridisation Double Fertilization Post-fertilization: Structures and Events Apomixis and Polyembryony 72 Important Points 74 Key Terms 75 Review Questions 76 NCERT Textbook Questions with Solutions 79 Higher Order Thinking Skills Questions with Solutions Human Reproduction Human Reproductive System Male Reproductive System Female Reproductive System Gametogenesis Spermatogenesis Oogenesis The Ovarian or the Menstrual Cycle Structure of Ova Fertilisation Changes from Egg to Embryo Development of Human Embryo Birth or Parturition 115

9 3.13 Lactation 116 Important Points 119 Key Terms 121 Review Questions 123 NCERT Textbook Questions with Solutions 130 Higher Order Thinking Skills Questions with Solutions Reproductive Health Problems and Strategies What is Reproductive Health? Reproductive Health Problems and Strategies Population Explosion Population Control Medical Termination of Pregnancy (MTP) Sexually Transmitted Diseases (STDs) Infertility Inequality of Sexes 149 Important Points 150 Key Terms 150 Review Questions 151 NCERT Textbook Questions with Solutions 153 Higher Order Thinking Skills Questions with Solutions 156 Unit Ii Genetics and evolution 0 5. Principles of Inheritance and Variation Mendel, the Founder of Genetics Mendel s Laws of Inheritance Inheritance of One Gene Inheritance of Two Genes Other Patterns of Inheritance and Genetic Expression Chromosomal Theory of Inheritance Linkage and Crossing Over Mapping on the Chromosomes Genetic or Linkage Maps Sex Determination Causes of Genetic Variation Pedigree Analysis Human Genetic Disorders Human Genetics 216 Important Points 220 Key Terms 222 Review Questions 224 NCERT Textbook Questions with Solutions 230 Higher Order Thinking Skills Questions with Solutions Molecular Basis of Inheritance Structure of Nucleic Acids (DNA and RNA) Structure of DNA (Deoxyribonucleic Acid) Structure of Chromosomes The Search for Genetic Material RNA World Replication of DNA 254

10 6.7 Transcription (DNA to RNA Synthesis) Genetic Code Protein Synthesis Regulation of Gene Expression Genomics Human Genome Project (HGP) DNA Fingerprinting Additional information on Gene Expression Gene Expressions in Prokaryotes 298 Important Points 303 Key Terms 304 Review Questions 306 NCERT Textbook Questions with Solutions 312 Higher Order Thinking Skills Questions with Solutions Evolutionary Biology Origin of Earth Theories on the Origin of Life Meaning of Evolution Evidences for Evolution Examples of Evolution by Natural Selection Artificial Selection Adaptive Radiations Biological Evolution Mechanism of Evolution Population Genetics and Evolution Mutations A Brief Account of Evolution Concept of Species Origin and Evolution of Man 367 Important Points 375 Key Terms 377 Review Questions 378 NCERT Textbook Questions with Solutions 384 Higher Order Thinking Skills Questions with Solutions 385 Unit iii biology and human welfare 0 8. Human Health and Disease Health and Its Importance Common Diseases in Humans Communicable Diseases Immunity Innate (non-specific) Immunity Acquired Immunity Vaccination and Immunisation Immune System Disorders Lymphoid Organs AIDS Cancer Adolescence and Drug/Alcohol Abuse 452

11 8.13 Alcohol Abuse Smoking and Tobacco 464 Important Points 467 Key Terms 468 Review Questions 470 NCERT Textbook Questions with Solutions 477 Higher Order Thinking Skills Questions with Solutions Strategies for Enhancement in Food Production Animal Husbandry Plant Breeding Main Steps in Breeding A New Genetic Variety Crop Improvement Single Cell Protein (SCP) Plant Tissue Culture Plant Tissue Culture Techniques 522 Important Points 527 Key Terms 527 Review Questions 528 NCERT Textbook Questions with Solutions 529 Higher Order Thinking Skills Questions with Solutions Microbes in Human Welfare Important Aspects of Microbes Microbes in Household Products Microbes in Industrial Products Microbes in Sewage Treatment Microbes in Production of Biogas Microbes as Biocontrol Agents Microbes as Biofertilisers 548 Important Points 551 Key Terms 551 Review Questions 552 NCERT Textbook Questions with Solutions 555 Higher Order Thinking Skills Questions with Solutions 557 Unit iv BIOTECHNOLOGY 11. Biotechnology: Principles and Processes Principles of Biotechnology Tools of Recombinant DNA (rdna) Technology Restriction Endonucleases Separation and Isolation of DNA Fragments Cloning Vectors or Vehicle DNA Competent Host Process of Recombinant DNA Technology 574 Important Points 579 Key Terms 580 Review Questions 580 NCERT Textbook Questions with Solutions 582 Higher Order Thinking Skills Questions with Solutions 585

12 12. Biotechnology and its Applications Biotechnological Applications in Agriculture Biotechnological Applications in Medicine Molecular Diagnosis Transgenic Animals Cloning Ethical Issues Biopatent Biopiracy Biowar 613 Important Points 618 Key Terms 618 Review Questions 619 NCERT Textbook Questions with Solutions 621 Higher Order Thinking Skills Questions with Solutions 623 Unit v ecology and environment 13. Organisms and Populations Definition of Ecology Levels of Organisation Organism and its Environment Major Biomes Major Abiotic Factors Response to Abiotic Factors Range of Tolerance Adaptations Populations Life History Variation Population Interactions Biotic Community Organisation Community Characteristics Analysis of Plant Communities 706 Important Points 709 Key Terms 712 Review Questions 714 NCERT Textbook Questions with Solutions 720 Higher Order Thinking Skills Questions with Solutions Ecosystem Ecosystem Structure and Function Productivity Decomposition Energy Flow Ecological Pyramids Ecological Efficiencies Ecological Succession Nutrient Cycling Biogeochemical Cycles Ecosystem Services 769 Important Points 771 Key Terms 772

13 Review Questions 774 NCERT Textbook Questions with Solutions 779 Higher Order Thinking Skills Questions with Solutions Biodiversity and Conservation Biodiversity Levels of Biodiversity Biogeographical Regions of India Magnitude of Diversity Patterns of Biodiversity Importance of Species Diversity to the Ecosystem Loss of Biodiversity Extinction of Species Causes of Biodiversity Losses Biodiversity Conservation Hotspots of Biodiversity International Efforts for Conserving Biodiversity Biodiversity Conservation in India 820 Important Points 821 Key Terms 822 Review Questions 823 NCERT Textbook Questions with Solutions 826 Higher Order Thinking Skills Questions with Solutions Environmental Issues Pollution Air Pollution Control of Air Pollution Controlling Vehicular Air Pollution: A Case Study of Delhi Noise Pollution Water Pollution and its Control Solid Wastes Agro-chemicals and their Effects Soil Pollution Radioactive Waste Radioactive Pollution Global Environmental Change Effects of Abundance of Greenhouse Gases Ozone Depletion in the Stratosphere Degradation (of soil) by Improper Resource Utilisation and Maintenance Deforestation Case Study of People s Participation in Conservation of Forests 889 Important Points 891 Key Terms 892 Review Questions 894 NCERT Textbook Questions with Solutions 898 Higher Order Thinking Skills Questions with Solutions 900 Value Based Questions Question Papers, 2013 (with solution) Question Papers, 2014 (with solution) Question Papers,

14 UNIT I REPRODUCTION

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