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

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11.

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


(i) Female XX with Male XO


The type of sex determination mechanism shown in female XX with male XO is male heterogamety

Example - Grasshopper 

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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.

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20.

How are 'sticky ends' formed on a DNA strand? Why are they so called?

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