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XII Biology Sample Paper, Set-10
SECTION-A 1. How many chromosomes are in a gamete of an organism that has 46 chromosomes in its cells? Ans. Gametes (n) have half the number of chromosomes found in the cells (2n). Hence, 2n = 46 then n = 23. 2. The mechanism to prevent the self pollen from fertilizing the ovules by inhibiting pollen germination or pollen tube growth, on the pistil. What is that mechanism? Ans. Self Incomp...

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XII Biology Sample Paper, Set-9
SECTION-A 1. Two villagers were arguing for the nutritive value of milk and curd? Being a normal science student and having studied the biochemistry of both the products, tell which one is more nutritive and justify it ? Ans. Curd is more nutritious because it have vitamin B12, and is synthesized by LAB (absent in milk). 2. What is ART? Ans. ART is Assisted Reproductive Technologies. 3. R...

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XII Biology Sample Paper, Set-8
SECTION-A 1. Define BOD. What does it indicate? Ans. Biological Oxygen Demand. It indicates presence of sewage in water. 2. 20 parrots, 50 sparrows and 150 crows are found in one part of seven senses garden which has large number of trees. Which parameter- species richness or species evenness can be easily assessed from this information? Ans. Species richness. 3. Why do farmers face the ...

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XII Biology Sample Paper, Set-7
SECTION-A 1. Why is internal fertilisation considered to be more advanced method than external fertilisation? Ans. Internal fertilisation ensures more chances of fertilisation with less wastage of gametes. 2. Which category of bacteria is used in production of bio-gas? Ans. Methanogens 3. What is hirudin? How do you get it?  Ans. Anti coagulant. Obtained from transgenic brassica napus....

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XII Biology Sample Paper, Set-6
SECTION-A 1. What is the special asexual reproductive structure in Chlamydomonas? Ans. Zoospores 2. What is the function of FIMBRIAE in fallopian tubes? Ans. "Fimbriae" are finger-like structures on the end of each tube,which helps in the collection of the ovum after ovulation. 3. Which tissue located inside the ovarian cavity? Ans. Placenta 4. Mendel followed a definite sequence of steps...

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XII Biology Sample Paper, Set-5
SECTION-A 1. What is emergency oral contraceptive? Ans. 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. Eg is i-pill. 2. Explain the process of MICROSPOROGENESIS. Ans. MICROSPOR...

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XII Biology Sample Paper, Set-4
SECTION-A 1. What are decomposers? Write their function. Ans. a) Saprotrophs feed on dead bodies of organisms, b) Decomposition and mineralization. 2. What is the difference between gaseous and sedimentary cycle? Ans. a) Gaseous-Reservoir in atmosphere ,Nitrogen cycle b) Sedimentary-Soil,e.g-phosphorus. 3. Why is the length of a food chain in an ecosystem generally limited to 3-4 trophic lev...

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XII Biology Sample Paper, Set-3
SECTION-A 1. Give the process of creation of r-DNA. Ans. Isolation - Digestion - Fractionation - Purification of the TARGET fragment - Cloning into vectors - Transformation of host cell and selection - Replication - Analysis - Expression of DNA. 2. Any DNA flanked at its two borders by T-DNA can be integrated into the plant genome. Name the vector used for this plant gene transfer? Ans. Tumor...

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XII Biology Sample Paper, Set-2
SECTION-A 1. What is water pollution? Ans. Water pollution :Biological Oxygen Demand (BOD) indicates the amount of dissolved oxygen utilised by the microorganisms for oxidising the oxdisable organic matter present in the water body. Greater the organics, greater would be the pollution and lesser the dissolved oxygen. 2. Define bio-magnification. Ans. Bio magnification Increase in concentratio...

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XII Biology Sample Paper, Set-1
SECTION-A 1. What name is given to the individuals that are produced from one individual and are genetically identical? Ans. Clone 2. What is the special asexual reproductive structure in Chlamydomonas? Ans. Zoospores 3. How does Penicillium (a fungus) reproduce asexually? Ans. Penicillum reproduces asexually by means of conidia. 4. Define pollution. Ans. Pollution: Any undesirable change...

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