Subject

Biology

Class

CBSE Class 12

Pre Boards

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Sample Papers

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 Multiple Choice QuestionsShort Answer Type

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11.

With the help of one example, explain the phenomena of co-dominance and multiple allelism in human population.


The phenomenon of multiple allelism and co-dominance is shown by the ABO blood group in human beings. The gene I for the blood group contains three alleles i.e. IA, IB and i which represents the phenomenon of multiple allelism as it has more than two alleles governing the same character. The alleles IA and IB  are co-dominant and express themselves even in the presence of the other. Thus the presence of both the alleles IA and IB gives the blood group of AB.

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12.

Write the scientific name of the fruit-fly. Why did Morgan prefer to work with fruit-flies for his experiments? State any three reasons.

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13.

Linkage or crossing-over of genes are alternatives of each other. Justify with the help of an example.

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14.

List the symptoms of Ascariasis. How does a healthy person acquire this infection?

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15.

Explain the significant role of the genus Nucleopolyhedrovirus in an ecological sensitive area.

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16.

How does a restriction nuclease function? Explain.

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17.

How have transgenic animals proved to be beneficial in:
(a) Production of biological products
(b)Chemical safety testing.

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18.

Describe the mutual relationship between fig tree and wasp and comment on the phenomenon that operates in their relationship.

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19.

Construct an age pyramid which reflects an expanding growth status of human population.

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20.

Make a list of any three out breeding devices that flowering plants have developed and explain how they help to encourage cross-pollination.

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