Subject

Biology

Class

CBSE Class 12

Pre Boards

Practice to excel and get familiar with the paper pattern and the type of questions. Check you answers with answer keys provided.

Sample Papers

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 Multiple Choice QuestionsShort 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. 


Brood parasitism is a type of parasitism in birds in which the parasitic bird lays its eggs in the nest of its host and lets the host incubate them. For example, cuckoo (koel) lay its eggs in the nest of crow. During the course of evolution, the eggs of the parasitic bird have evolved to resemble the hosts egg in size and colour to reduce the chances of the host bird detecting the foreign eggs and ejecting them from the nest.

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