Single-celled Paramecium live in pond water (a hyposmotic environment relative to the cytosol). They have a structural feature, a contractile vacuole, that enables them to osmoregulate. If sucrose or sodium chloride was added to the pond water, at which final concentration is the contractile vacuole likely to be most active?

Question

Quizplus · Accepted Answer

In a hyposmotic environment, water tends to enter the Paramecium by osmosis. The contractile vacuole expels excess water to maintain osmotic balance. At 0.0 mM sucrose, the environment remains most hyposmotic, causing the vacuole to be most active.

Single-Celled Paramecium Live in Pond Water (A Hyposmotic Environment Relative