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

Download the PDF Sample Papers Free for off line practice and view the Solutions online.
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 Multiple Choice QuestionsShort Answer Type

11.

In a cross between two tall pea plants some of the off-springs produced were dwarf. Show with the help of Punnett square how this is possible.

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12.

A student on a school trip started sneezing and wheezing soon after reaching the hill station for no explained reasons. But, on return to the plains, the symptoms disappeared. What is such a response called? How does the body produce it?

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13.

Name two commonly used bioreactors. State the importance of using a bioreactor.

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14.

Write the function of adenosine deaminase enzyme. State the cause of ADA deficiency in humans. Mention a possible permanent cure for ADA deficiency patient.

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15.

Expand the following and mention one application of the following

(i) PCR (ii) ELISA

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16.

(a) Mention the difference in the mode of action of exonuclease and endonuclease.

(b)How does restriction endonuclease function?


The difference between the mode of action of endonuclease and exonuclease is that Exonuclease removes nucleotides from the ends of the DNA whereas Endonuclease makes cut at specific positions within the DNA.

(b) Restriction endonuclease functions by inspecting the entire length of the DNA sequence. When it finds the specific recognition sites it binds to the DNA molecule and cuts both the strands at specific palindromic sites in their sugar-phosphate backbone.

e.g. Eco R1 cuts the DNA at following pallindromic sequences.

               |

        5' G A A       T T C   3'

        3' C T T       A A G 5'

                                   |  

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17.

Name any two sources of e-Wastes and write two different ways for their disposal.

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18.

Why the pyramid of energy is always upright? Explain.

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19.

Explain why very small animals are rarely found in polar region.

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20.

Draw a diagram of the microscopic structure of human sperm. Label the following parts in it and write their functions.

(a) Acrosome

(b) Nucleus

(c) Middle piece

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