Based on the plasmodium life cycle shown in figure 21–4, what would happen if the mosquitoes disappeared?
a. plasmodium merozoites would form, but gametes would not form.
b. the plasmodium life cycle would continue, and humans would become the only host.
c. plasmodium infection would continue because it will be passed from person to person.
d. the plasmodium life cycle would be interrupted, and the infection could not be passed on.

The answer is D. The Plasmodium life cycle would be interrupted, and the infection could not be passed on.

Mosquitoes are necessary for malaria infection. According to the lyfe cycle, after infected mosquitoes bite a human, they inject saliva with sporozoites into the human circulatory system (stage A). The sporozoites enter human liver where they divide and schizonts are created. Schizonts give birth to merozoites (stage B). Merozoites are released into the bloodstream where invade red blood cells (stage C). Inside the red blood cells, they evolve into trophozoites, they into erythrocytic schizonts, and finally into a new generation of merozoites (stage D). After the red blood cells rupture, they are released into the blood stream (stage E). Therefore, if mosquitoes disappear, the first stage (stage A) will be missing, so the plasmodium life cycle will be interrupted.