Which of the following diagrams best represents the net movement of water molecules during osmosis across a selectively permeable membrane?

• A. Water molecules move from an area of high solute concentration to an area of low solute concentration.
• B. Water molecules move from an area of low solute concentration to an area of high solute concentration.
• C. Solute molecules move from an area of low solute concentration to an area of high solute concentration.
• D. Both water and solute molecules move equally in both directions across the membrane.

Answer: (B)

Verified step by step guidance

1. Understand the concept of osmosis: Osmosis is the movement of water molecules across a selectively permeable membrane from an area of low solute concentration to an area of high solute concentration. This occurs to balance the solute concentrations on both sides of the membrane.
2. Identify the key principle: Water moves to dilute the higher solute concentration, not the solute itself. Solute molecules generally do not move during osmosis unless facilitated by other processes like diffusion.
3. Analyze the options: The first option incorrectly states that water moves from high solute concentration to low solute concentration, which contradicts the principle of osmosis. The second option correctly describes the movement of water during osmosis. The third option incorrectly describes solute movement, which is not the primary focus of osmosis. The fourth option incorrectly suggests equal movement of both water and solute molecules, which is not characteristic of osmosis.
4. Relate the concept to the diagram: The correct diagram should show water molecules moving from the side with lower solute concentration to the side with higher solute concentration, across the selectively permeable membrane.
5. Conclude the reasoning: Based on the principles of osmosis, the correct answer is the second option, as it accurately describes the net movement of water molecules during osmosis.