Question

the paramecium is a single - celled freshwater protist that responds to changes in its environment in order to maintain homeostasis. the contractile vacuole actively pumps water out in order to prevent the cell of the paramecium from lysing (bursting) when excess water flows into the cell. a student tests the action of the paramecium under water levels of varying salinity. which hypothesis correctly describes the predicted activity of the contractile vacuole under changing water and solute concentrations? a as the solute concentration of the water increases, the rate of contractions by the vacuole will increase b as the solute concentration of the water increases, the rate of contractions by the vacuole will decrease c as the solute concentration of the water decreases, the rate of contractions by the vacuole will decrease d as the solute concentration of the water decreases, the rate of contractions by the vacuole will remain the same

Explanation:

The contractile vacuole pumps out excess water to prevent cell lysis. When the solute concentration of the surrounding water increases, the water potential of the surrounding environment increases relative to the cell. So, less water enters the paramecium cell by osmosis, and thus the contractile vacuole has to contract less frequently to expel water.

Answer:

B. As the solute concentration of the water increases, the rate of contractions by the vacuole will decrease