Which term describes the diffusion of water across a selectively permeable membrane?

Which term describes the diffusion of water across a selectively permeable membrane?

• A. Diffusion of water across membranes
• B. Diffusion of water
• C. Active transport of water
• D. Osmosis

Answer: (D)

Osmosis is the movement of water across a selectively permeable membrane from a region of lower solute concentration to higher solute concentration. The membrane lets water through but restricts many solutes, so water shifts to balance the solute levels. It’s a passive process, not requiring energy. For example, a plant cell in pure water takes in water by osmosis and becomes turgid, while in a salty solution water leaves the cell. Saying “diffusion of water across membranes” is less precise because osmosis specifically describes water moving through a semipermeable membrane driven by solute differences.

Osmosis is the movement of water across a selectively permeable membrane from a region of lower solute concentration to higher solute concentration. The membrane lets water through but restricts many solutes, so water shifts to balance the solute levels. It’s a passive process, not requiring energy. For example, a plant cell in pure water takes in water by osmosis and becomes turgid, while in a salty solution water leaves the cell. Saying “diffusion of water across membranes” is less precise because osmosis specifically describes water moving through a semipermeable membrane driven by solute differences.