Which statement about osmosis is not listed as a requirement in the material?

• A. It requires a gradient and a selectively permeable membrane
• B. Water moves to area of greater solvent concentration
• C. It involves movement of water across a semipermeable barrier
• D. It can occur without a membrane

Answer: (D)

Osmosis is the movement of water across a semipermeable membrane in response to differences in solute concentration, creating an osmotic gradient. Water moves toward the side with more dissolved substances (lower water potential), and the membrane is what makes this process osmosis rather than simple diffusion of water. Because a semipermeable barrier that allows water to pass while restricting solutes is essential to drive this flow, the statement that osmosis can occur without a membrane is not correct. The remaining statements reflect the needed conditions: there is a gradient, and water moves across a semipermeable barrier.