Subject

Biology

Class

CBSE Class 12

Pre Boards

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Sample Papers

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CBSE Class 12 Biology Solved Question Paper 2012

Short Answer Type

11.

(a) Mention the cause and the body system affected by ADA deficiency in humans.

(b) Name the vector used for transferring ADA-DNA into the recipient cells in humans. Name the recipient cells.

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12. Name the source organism that possesses Taq polymerase. What is so special about the function of this enzyme?

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13. State one advantage and one disadvantage of cleistogamy.

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14. How did Ahmed Khan, plastic sacks manufacturer from Bangalore, solve the ever-increasing problem of accumulating plastic waste?

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15. Name the source of cyclosporin-A. How does this bioactive molecule function in our body?

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16.

(a) Name the group of viruses responsible for causing AIDS in humans. Why are these viruses so named?

(b) List any two ways of transmission of HIV infection in humans, other than sexual contact.

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17.

(a) Draw a neat labelled diagram of a nucleosome.

(b) Mention what enables histones to acquire a positive charge.

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18. Name any two organisms that are responsible for ringworms in humans. Mention two diagnostic symptoms. Name the specific parts of the human body where these organisms thrive and explain why.

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19. Explain brood parasitism with the help of an example.

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20. Differentiate between perisperm and endosperm giving one example of each.

Perisperm	Endosperm
Perisperm is the remnant of nucellus which are persistent. It encloses the embryo and provides nourishment to it in certain seeds.	Endosperm is the tissue formed after double fertilisation. It surrounds, stores food and provide nourishment to the embryo in an angiosperm seed.
It is diploid in nature.	It is triploid in nature because it is formed as a result of triple fusion.
Example- Black pepper	Example- Wheat