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Biology Theory 2010 Question Paper For CBSE Class XII Exams

Section A

1. Mention the site where syngamy occurs in amphibians and reptiles respectively. (1 Marks)

2. How is snow – blindness caused in humans? (1 Marks)

3. Name one autosomal dominant and one autosomal recessive Mendel an disorder in Humans. (1 Marks)

4. How is the action of exonucluease different from that of end nuclease? (1 Marks)

5. India has more than 50,000 strains of rice. Mention the level of biodiversity it represents. (1 Marks)

6. Mention the information that the health workers derive by measuring BOD of a water Body. (1 Marks)

7. Name the enzyme involved in the continuous replication of DNA strand. Mention the Polarity of the template strand. (1 Marks)
8. Of springs derived by asexual reproduction are called clones. Justify giving two Reasons. (1 Marks)

Section B

1. Mention the role o ribosome's in peptide -bond formation .How does ATP facilitate it? (2 Marks)
2. How do copper and hormone releasing IUDs act as contraceptives? Explain. (2 Marks)
3. If you squeeze a seed of orange you might observe many embryos of different sizes. How is it possible? Explain. (2 Marks)
4.  A recombinant DNA is formed when sticky ends of vector DNA and foreign DNA join.   Explain how the sticky ends are formed and get joined.(2 Marks)
5.  (i) Mention the number of primers required in each cycle of polymerase chain  Reaction (PCR) . Write the role of primers and DNA polymerase in PCR.(2 Marks)
   (ii) Give the characteristic feature and source organism of the DNA polymerase  Used in PCR. (2 Marks)
6. Define the term ‘health’ Mention any two ways of maintaining it. (2 Marks)

   OR

    Why does a doctor administer tetanus antitoxin and not a tetanus vaccine to a child injured in a roadside accident with a bleeding wound ? Explain.(2 Marks)

7. Giving two reasons explain why there is more species biodiversity in tropical latitudes than in temperate ones. (2 Marks)
8. Name an upload drug and its source plant. How does the drug affect the human body? (2 Marks)
9. Mention the major cause of air pollution in metro cities. Write any three ways by which it can be reduced. (2 Marks)
10. How did Eli Lilly synthesize the human insulin? Mention one difference between this insulin and the one produced by the human pancreas. (2 Marks)