The Indian Community School Kuwait 2nd Term examination Marking Scheme Sub: Biology Marks: 70 SECTION: A

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3 The Indian Community School Kuwait 2nd Term examination Marking Scheme Class XII Time: 3hrs Sub: Biology Marks: 70 SECTION: A 1. One of them (exonucleases) added methyl groups to DNA. The other (endonucleases) cut at specific points within the DNA. ½ + ½ = 1 2. Origin of replication (Ori) Birds, are eurythermals and can tolerate a wide range of temperatures. ½ + ½ =1 4. Predation Lichens, they secrete acids to dissolve the rock and help in weathering and soil formation and pave way to bryophytes. 1 SECTION: B 6. (a) 3 CTTAAG 5 (b) EcoRI. 1+1 = 2 7. Biopiracy definition. 1 Indian Parliament has passed the second amendment of the Patent Bill which deals with Patent terms, emergency provisions and research and development initiatives Phenotypic adaptation refers to a characteristic feature in the external appearance/manifestation of a characteristic that is generally controlled. 1 ½. Eg: Leaves are modified in to spines in Opuntia. ½ 9. Refer page No: 224 of NCERT reader under conform. 2 OR Through its internal oxidation of fat in which water is a byproduct. It can concentrate its urine, so that only minimal volume of water is removed during excretion of wastes Man can occupy two different trophic levels. When he depends only on vegetarian food (plants), he occupies second trophic level and is a primary consumer. Plants > Man When he eats the flesh of some animals (non vegetarian food), he occupies the third trophic level and is secondary consumer. Plants Goat Man 2

4 11. Hot spots are the regions with very high levels of species richness and high degree of endemism and need maximum protection. 1 Eg: Western ghats and Himalayas Refer page No. 272, 1 st para of NCERT reader. 1 ½ Unleaded petrol is the best fuel. ½ SECTION : C 13. When a restriction enzyme cuts the strands of DNA, a little away from the center of the palindrome site, between the same two bases on the two strands, single stranded portions are left at the ends. These over hanging single stranded stretches of DNA at the ends are called sticky ends. They are so called because they easily form hydrogen bonds with their complimentary cut counter parts with the action of enzyme ligase = Ref. Page No.198 of NCERT reader Gel electrophoresis. 3 OR Agrobacterium tumefaciens is able to deliver a piece of DNA, called T DNA in to the plant cells and transform them in to tumor cells The tumor inducing (Ti) plasmid of the bacterium is modified and made nonpathogenic. Though it is non pathogenic, it still has the capacity to deliver its Ti plasmid to the plants and hence, the genes of interest ligated to it The living organisms plants, animals, fungi or bacteria whose DNA has been manipulated to possess and express a foreign DNA. 1 Any two points Refer NCERT reader page No. 208 under GMO By increasing RBC production. Decreasing the binding capacity of hemoglobin and by increasing the breathing rate Refer Page No. 225 of NCERT reader (a) i.per cent cover.ii. number caught per trap for fishes. Iii. Pugmarks or fecal pellets for tiger censes. ½ + ¾ + ¾ (b) Tells us about the status of a species, i.e. the outcome of competition, impact of predation or effect of pesticides etc. 1

5 Productivity refers to the rate of biomass production. Gross primary productivity is the rate of production of organic matter during photosynthesis.

6 Gross primary productivity minus the respiratory losses is net primary productivity. i.e. GPP R = NPP 3 23.The first Earth summit was held in Rio de Janeiro in Objectives were: (i) Conservation of biodiversity, and (ii) Sustainable utilization of the benefits from biodiversity When DDT is sprayed on the crop plants, it remain in the soil as it is non biodegradable and enters the plant. As it travels through food chain, it undergoes biomagnification, i.e. increase in concentration at successive higher tropic levels, as it can neither be metabolized nor excreted; this causes disorders in those organisms. In birds, a high concentration of DDT interferes with calcium metabolism and causes thinning of egg shells leading to their premature breaking; consequently there is a decline in bird population. 3 Section: D 25. (i) Agrochemical based agriculture, using chemical fertilizers and pesticides. Organic agriculture, using biofertilizers, biopesticides, vermi composting, etc. Genetically engineered (GM) crops based agriculture. (ii) Use of improved hybrid crop varieties. Better management practices. Use of agrochemicals (pesticides and fertilisers). (iii) The agrochemicals cause pollution of soil and water and reduce the yield in the long run; they are too expensive for the farmers. Further increase in the yield of the existing varieties by conventional breeding is not possible. 5 OR Transgenic animals are those animals which have their DNA manipulated to posses and express one/more foreign gene(s). They are produced for the following purpose: (i) Transgenic animals are designed to allow the study of how genes are regulated and how they affect the normal functions of the body and its development, e.g. Information has been obtained as to how insulin has a role as growth factor. (ii) Transgenic animals that produce useful biological compounds are created by introducing a portion of the DNA that codes for the product, e.g. α I antitrypsin is produced for treating emphysema. (iii) Transgenic animals are being developed to test the safety of vaccines, e.g. polio vaccine has been tested on transgenic mice. (iv) Transgenic animals with more sensitivity to toxic substances are being developed to test the toxicity of drugs. 5

7 26. The arguments to conserve biodiversity fall into three categories. (i) Narrowly utilitarian, i.e. humans, derive a number of direct economic benefits from nature, like food, fibre, industrial products. (ii) Broadly utilitarian, i.e. the biodiversity provides many ecosystem services like, adding oxygen to the atmosphere, pollination of plants for fruit and seed formation. (iii) Ethical arguments relates to our moral duty to care for the well being of all the plants, animals and microbes of the plant and pass on the biological legacy to the future generation. We can conserve biodiversity in two ways. (iv) Insitu conservation means we conserve and protect the whole ecosystem. (v) Ex situ conservation in which the threatened and animals and plants are removed from the natural habitat and placed and placed in special setting where they can be protected and given special care. 5 OR (i) Habitat loss and fragmentation. It is the primary cause for extinction. The tropical rain forests initially covered 14% of the land surface of the earth, but now they cover only 6% of land area. Total loss of a habitat deprives many animals and plants of their homes and they face extinction. When a large habitat becomes fragmented animals requiring large territories and those with certain migratory habits start decreasing. (ii) Over exploitation When nature is overexploited by man for the natural resources, many species become extinct. (iii) Invasion by Alien Species. The alien species become invasive and compete with native species and cause extinction of indigenous species. (iv) Co extinction Co extinction is a phenomenon in which when a species becomes extinct, the plant and animal species associated with it in an obligatory manner, also become extinct. 5

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