(a) 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.
(b) What are interferons ? Mention their role.

Explanation

(a) This kind of immunity is referred to as acquired immunity. This immunity is charaeterised by memory for the pathogen so a childhood disease such as chicken pox is not contracted in adulthood.