Question

which of the following best describes osmosis?
○ diffusion of water from a greater to a lesser water concentration across a selectively permeable membrane
○ movement of water into a solute
○ active transport of water across the cell membrane
○ diffusion of water from a greater to a lesser water concentration
○ random movement of water due to kinetic energy

Explanation:

To determine the best description of osmosis, we analyze each option:

• Option 1: Osmosis is the diffusion (passive movement) of water across a selectively permeable membrane from an area of higher water concentration (lower solute concentration) to an area of lower water concentration (higher solute concentration). This matches the definition.
• Option 2: Osmosis is not simply "movement of water into a solute" as it involves a membrane and concentration gradients, not just moving into a solute.
• Option 3: Osmosis is passive transport, not active transport (which requires energy). So this is incorrect.
• Option 4: Osmosis specifically requires a selectively permeable membrane. This option lacks the membrane component, so it's incomplete.
• Option 5: Random movement due to kinetic energy describes Brownian motion or general diffusion, not osmosis which has a directional movement across a membrane based on water concentration.

Answer:

A. diffusion of water from a greater to a lesser water concentration across a selectively permeable membrane