Which process requires a carrier protein to facilitate the movement of molecules across the cell membrane?

• A. Osmosis
• B. Facilitated diffusion
• C. Simple diffusion
• D. Active transport

Answer: (B)

Verified step by step guidance

1. Understand that the cell membrane is selectively permeable, allowing certain molecules to pass through while blocking others.
2. Recognize that facilitated diffusion is a type of passive transport that does not require energy, unlike active transport.
3. Identify that facilitated diffusion involves the use of carrier proteins or channel proteins to help move molecules across the cell membrane.
4. Differentiate facilitated diffusion from simple diffusion, which does not require any proteins and occurs directly through the lipid bilayer.
5. Conclude that facilitated diffusion is the process that requires a carrier protein to assist in the movement of molecules across the cell membrane.