Which statement best describes the difference between osmosis and diffusion in passive transport?

• A. Osmosis is the movement of any molecules from low to high concentration, while diffusion is only the movement of water across a membrane.
• B. Diffusion occurs only across selectively permeable membranes, while osmosis can occur in any space without a membrane.
• C. Diffusion is the movement of solute particles down their concentration gradient, while osmosis is the diffusion of water across a selectively permeable membrane toward higher solute concentration.
• D. Diffusion requires ATP to move molecules across a membrane, while osmosis is always passive and occurs only in animal cells.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the definitions of diffusion and osmosis in the context of passive transport. Diffusion is the movement of solute molecules from an area of higher concentration to an area of lower concentration, without the use of energy.
2. Step 2: Recognize that osmosis is a specific type of diffusion that involves the movement of water molecules across a selectively permeable membrane toward an area with a higher solute concentration.
3. Step 3: Note that both diffusion and osmosis are passive processes, meaning they do not require ATP or energy input from the cell.
4. Step 4: Identify that diffusion can occur with various solutes and does not necessarily require a membrane, whereas osmosis specifically involves water moving through a selectively permeable membrane.
5. Step 5: Compare the given statements to these principles and determine that the correct description is: Diffusion is the movement of solute particles down their concentration gradient, while osmosis is the diffusion of water across a selectively permeable membrane toward higher solute concentration.