Which modification would allow only the green solutes to diffuse across the membrane during passive transport?

• A. Increase the temperature to speed up all solute movement.
• B. Use ATP to actively pump green solutes across the membrane.
• C. Decrease the concentration of green solutes outside the membrane.
• D. Add a membrane protein that specifically transports green solutes.

Answer: (D)

Verified step by step guidance

1. Understand the concept of passive transport: Passive transport is the movement of molecules across a membrane without the use of energy (ATP). It relies on concentration gradients and does not involve active pumping.
2. Recognize the role of membrane proteins: Membrane proteins can act as channels or carriers that facilitate the movement of specific solutes across the membrane during passive transport. These proteins are selective and allow only certain molecules to pass through.
3. Analyze the options provided: Increasing temperature speeds up all solute movement, not just green solutes. Using ATP involves active transport, which is not passive transport. Decreasing the concentration of green solutes outside the membrane would reduce diffusion rather than facilitate it.
4. Identify the correct modification: Adding a membrane protein that specifically transports green solutes would allow only the green solutes to diffuse across the membrane during passive transport. This is because the protein provides a selective pathway for the green solutes.
5. Conclude the reasoning: The addition of a specific membrane protein aligns with the principles of passive transport and ensures selective diffusion of green solutes without requiring energy input.