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.
Advertisement

 Multiple Choice QuestionsShort Answer Type

11.

Out of many papaya plants growing in your garden, only a few bear fruits. Give reason.

4030 Views

Advertisement

12.

Write the two limitations of traditional breeding technique that led to promotion of micro-propagation.


Two limitations of traditional breeding technique that led to promotion of micro-propagation are :

i. It was difficult to maintain purity of offspring produced by traditional breeding techniques.
ii. The traditional breeding methods took a long time and did not produce many offsprings. 

2466 Views

Advertisement
13.

Mention two advantages of micro propagation.
Give two examples where it is commercially adopted.

1961 Views

14.

It is generally observed that the children who had suffered from chicken - pox in their childhood may not contract the same disease in their adulthood. Explain giving reasons the basis of such an immunity in an individual. Name this kind of immunity.

1951 Views

Advertisement
15.

 What are interferons ? Mention their role.

2282 Views

16.

How do homologous organs represent divergent evolution ? Explain with the help of a suitable example.

2540 Views

17.

Name two hormones that are constituents of contraceptive pills. Why do they have high and effective contraceptive value ? Name a commonly prescribed non-steroidal oral pill.

2596 Views

18.

(a) What do 'Y' and 'B' stand for in 'YAC' and 'BAC' used in Human Genome Project (HGP). Mention their role in the project.
(b) Write the percentage of the total human genome that codes for proteins and the percentage of discovered genes whose functions are known as observed during HGP.
(c) Expand 'SNPs' identified by scientists in HGP.

3166 Views

Advertisement
19.

Explain enzyme-replacement therapy to treat adenosine deaminase deficiency. Mention two disadvantages of this procedure. 

1685 Views

20.

What is a test cross? How can it decipher the heterozygosity of a plant?

2413 Views

Advertisement