Apentix/AP Biology/Unit 2: Cell Structure and Function/Question
AP Biologyeasymcq1 pt

Which of these moves substances across a membrane with no expenditure of cellular energy?

A.Export of a hormone droplet when a vesicle fuses with the membrane
B.Importing a bacterium by wrapping the membrane around it
C.Accumulating potassium inside the cell far above its outside level
D.Uptake of water by a cell bathed in a solution more dilute than its cytosol

Explanation

Core Concept

A dilute bath has higher water potential than the cytosol, so water flows inward by osmosis, a purely passive process that needs no ATP. Channels and the bilayer itself conduct this movement. The other listed options all require energy to push material against a gradient or to reshape the membrane.

Correct Answer

DUptake of water by a cell bathed in a solution more dilute than its cytosol

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