Question

Which of the following statements about contractile vacuoles is true?

a. They are important for acquiring food
b. They are a mechanism for defense
c. They are a mechanism for removing excess water from the organism
d. They are more important in marine protists than they are in freshwater protists

Answer 1

Contractile vacuoles are a mechanism for removing excess water from the organism, specifically in freshwater protists. They absorb water through canals from the cytoplasm and pump it out of the cell when the vacuole is full.

Step-by-step explanation:

Contractile vacuoles are a mechanism for removing excess water from the organism. They are found in freshwater protists such as the paramecium, which live in a hypotonic environment and need to prevent their cells from taking in too much water by osmosis. The contractile vacuole absorbs water through canals from the cytoplasm and then pumps it out of the cell when the vacuole is full.