Which statement about osmosis is true?

• A. It moves solutes other than water
• B. It requires energy input
• C. It moves water across a semi-permeable membrane from higher to lower water potential
• D. It occurs only in animal cells

Answer: (C)

Osmosis is the diffusion of water across a selectively permeable membrane. The key idea is that water moves from a region of higher water potential to a region of lower water potential, and the membrane lets water pass while blocking many solutes. So water shifts to the side with more dissolved substances, helping to balance the potentials without the input of energy. This is why the statement is true: water crosses the membrane from higher to lower water potential through a semi-permeable membrane.

Remember that osmosis is about water movement, not solute movement; it happens in plant, animal, and microbial cells wherever a selectively permeable barrier separates solutions of different solute concentrations.