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Class 12th Biology 2012 Set1 Outside Delhi Board Paper Solution

Question 24

Trace the life cycle of malarial parasite in the human body when bitten by an infected female Anopheles.

(i) Malaria is caused by the biting of female Anopheles mosquito to the healthy human being releasing Plasmodium, which lives in an infectious form (sporozoite).
(ii) First it undergoes asexual reproduction when the parasites burst the liver cells by multiplying itself that are released into the blood.
(iii) Again it bursts the RBC by entering the RBC cells multiplying by the means of asexual reproduction.
(iv) Along with the bursting of RBC cells, a toxic element called haemozoin is released that causes chill in the body of the human being.
(v) Gametocytes multiply forming from the sporozoites that multiply sexually.
(vi) Gametocytes are introduced into the mosquito when the female Anopheles mosquito bites the diseased person.
(vii) Gametocytes again form sporozoites by fertilizing inside the intestine of the mosquito.
(viii) These sporozoites are stored in the salivary glands of mosquito and are released when the healthy person is bitten by this mosquito.