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CBSE Class 12 Biology Solved Question Paper 2014

Short Answer Type

11.

Write the types of sex-determination mechanisms the following crosses show. Give an example of each type

(i) Female XX with Male XO

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12.

Write the types of sex-determination mechanisms the following crosses show. Give an example of each type

(ii) Female ZW with Male ZZ

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13.

Name the scientist who suggested that the genetic code should be made of a combination of three nucleotides.

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14.

Explain the basis on which he arrived at this conclusion.

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15.

State the disadvantage of inbreeding among cattle. How it can be overcome?

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16.

Explain with the help of a suitable example the naming of a restriction endonuclease.

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17.

State how Agrobacterium tumifaciens has been made a useful cloning vector to transfer DNA to plant cells.

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18.

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

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19.
Apart from being a part of the food chain, predators play other important roles. Mention any two such roles supported by examples.

Predators play an important role in:

1. Maintaining the prey population and regulating intra-species competition. For example, if tigers are removed from a forest, spotted deer will multiply rapidly.

2. Indicating ecological disturbances. Usually, predators are small in number and highly sensitive to ecological changes, owing to their excessive adaptation. For example, Gharials (freshwater predators) start dying rapidly as soon as a river starts getting polluted, thus indicating a disturbance in the ecosystem.

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