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

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

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

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.

15.

 What are interferons ? Mention their role.

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

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.

(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.

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

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