Question

(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. [3]

Answer 1

(a) The type of immunity is active immunity. [0.5]
When exposed to the pathogen for the first time, the primary immune response casues the release of the relevant antibodies against the pathogen. Some memory cells are created. These help to prevent the second recurrence of the disease in adulthood by eliciting a highly intensified secondary response. [1]

(b) Interferon : These are proteins made and released by viral infected cells which protect other non-infected cells from viral infection. [0.5]

Role of interferons - They help in preventing viral infection of the adjoining cells. They are also given to cancer patients to destroy tumour as it activates the immune system. [1]