Question

Fill in the blanks with appropriate words.
Contractile vacuoles are absent in .......... protozoans.

Answer 1

Contractile vacuoles used to store excess water and maintain the concentration of body fluid by removing excess water by a process of endosmosis. But marine protozoa have a hypertonic external environment they do not possess a problem of excess endosmosis instead they have to conserve their water content from getting lost in the environment.

So the correct answer is 'marine protozoa'