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Q.
Signet ring stage is found in
UP CPMTUP CPMT 2010Human Health and Disease
Solution:
In Plasmodium life cycle, when metacryptozoite enters into an erythrocyte $(RBC)$, it becomes a rounded young trophozoite. As it grows, a large non contractile vacuole appears in its centre in its centre, pushing the cytoplasm and nucleus to a thin peripheral layer to give a signet-ring appearance to the trophozoite.