You are watching a Paramecium in fresh water and see a rounded structure within it enlarge and then suddenly contract as water is expelled.You have just witnessed the
A) food vacuole releasing excess water acquired through eating.
B) oral groove expelling water as food is ingested.
C) result of ciliary action involved in locomotion.
D) contractile vacuole keeping the organism's cytoplasm hypertonic to the environment.
E) expulsion of waste produced during digestion.

Question

Quizplus · Accepted Answer

The description given - a rounded structure within the Paramecium enlarging and then suddenly contracting as water is expelled - describes the function of a contractile vacuole. Contractile vacuoles help regulate the osmotic balance of the Paramecium by expelling excess water and keeping the cytoplasm hypertonic to the environment.

You Are Watching a Paramecium in Fresh Water and See