Q.82 Malaria is caused by Plasmodium species, which is a parasite having a complex life cycle. The fusion
between male and female gametocytes of Plasmodium happens inside
(A) human liver
(B) human RBCs
(C) mosquito midgut
(D) mosquito salivary glands
Malaria, caused by Plasmodium species, involves a complex life cycle split between humans and mosquitoes. The fusion of male and female gametocytes occurs inside the mosquito midgut, marking the start of the parasite’s sexual phase.
Correct Answer
The correct answer is (C) mosquito midgut. Male microgametocytes and female macrogametocytes, taken up from human blood during a mosquito’s meal, activate in the mosquito’s midgut. Here, microgametes fertilize macrogametes to form a zygote, initiating sporogony.
Life Cycle Overview
Plasmodium’s cycle alternates asexual reproduction in humans and sexual stages in Anopheles mosquitoes. In humans, sporozoites from mosquito saliva target the liver, then red blood cells (RBCs) for merozoite multiplication. Mature gametocytes in RBCs enter the mosquito vector for sexual fusion.
Option Analysis
| Option | Explanation | Correct? |
|---|---|---|
| (A) human liver | Liver hosts pre-erythrocytic schizogony where sporozoites multiply into merozoites; no gametocyte fusion occurs here. | No |
| (B) human RBCs | Gametocytes mature inside human RBCs, but remain dormant until mosquito ingestion; fusion does not happen in RBCs. | No |
| (C) mosquito midgut | Gametocytes activate post-ingestion; male forms flagellated microgametes that fuse with female macrogametes in the midgut. | Yes |
| (D) mosquito salivary glands | Zygotes develop into ookinetes, oocysts, sporozoites in midgut wall, then migrate to salivary glands; fusion precedes this. | No |
Exam Preparation Tips
Understand Plasmodium stages: liver (exo-erythrocytic), blood (erythrocytic with gametocytes), mosquito (sporogonic). Focus on vector stages for questions like this in biology exams.
