Question

multiple choice 1 point for osmosis to occur, ____. a concentration gradient cannot exist a selectively permeable membrane must be present pure water must be on one side of the membrane only solutes can pass through the membrane cellular energy must be expended

Explanation:

Osmosis is the diffusion of water across a selectively permeable membrane. Let's analyze each option:

• "a concentration gradient cannot exist": Osmosis requires a concentration gradient (difference in solute concentration) to drive water movement, so this is incorrect.
• "a selectively permeable membrane must be present": This is a key requirement for osmosis, as it allows water (and not all solutes) to pass, enabling the movement down the concentration gradient.
• "pure water must be on one side of the membrane": Osmosis can occur between solutions of different solute concentrations, not necessarily with pure water on one side, so this is incorrect.
• "only solutes can pass through the membrane": In osmosis, water (solvent) passes, not just solutes, so this is incorrect.
• "cellular energy must be expended": Osmosis is a passive process (no energy required), so this is incorrect.

Answer:

B. a selectively permeable membrane must be present