Which statement about osmosis is true?

• A. It requires energy to move water.
• B. It moves solutes from high to low concentration.
• C. It moves water from low to high water potential.
• D. It moves water across a semipermeable membrane from high to low water potential.

Answer: (D)

Osmosis is the passive movement of water across a selectively permeable membrane. Water moves from regions of higher water potential (less solute, more free water) to regions of lower water potential (more solute, less free water). The membrane allows water to pass but often restricts solutes, so the direction of flow follows the water potential gradient. Because this is driven by the gradient rather than energy input, no external energy is required. The statement that best fits is the one that describes water crossing a semipermeable membrane from high to low water potential. It’s not about moving solutes, and it doesn’t go from low to high water potential.