Which statement about osmosis is true?

• A. Osmosis requires energy input.
• B. Osmosis is diffusion of water across any membrane.
• C. Osmosis moves solutes from low to high concentration.
• D. Osmosis is diffusion of water across a selectively permeable membrane from area of higher water potential to lower.

Answer: (D)

Osmosis is the passive diffusion of water across a selectively permeable membrane from an area of higher water potential to an area of lower water potential. This means water moves toward solutions with more solutes (lower water potential) until balance is approached, and it doesn’t require energy. The statement that describes diffusion of water across a selectively permeable membrane from higher to lower water potential accurately captures what drives osmosis and the membrane requirement. The other ideas miss key points: osmosis moves water, not solutes; it doesn’t need energy input; and it only occurs across membranes that water can cross while solutes may be restricted.