Question

question: which of the following is true of facilitated diffusion? answer options: select one of four it needs a semipermeable membrane. it needs energy. it needs carrier proteins. it loses or gains an electron.

Explanation:

• For "It needs a semipermeable membrane": All types of diffusion (including simple and facilitated) occur across a semipermeable cell membrane, but this is not a defining characteristic unique to facilitated diffusion. Simple diffusion also occurs across the semipermeable membrane.
• For "It needs energy": Facilitated diffusion is a passive transport process, meaning it does not require energy (ATP). Molecules move down their concentration gradient.
• For "It needs carrier proteins": Facilitated diffusion involves the movement of molecules (like polar molecules or ions) across the cell membrane with the help of carrier proteins or channel proteins. This is a key feature that distinguishes it from simple diffusion (which does not need proteins) and from active transport (which needs energy).
• For "It loses or gains an electron": Gaining or losing electrons is related to redox reactions, not facilitated diffusion. Facilitated diffusion is about the movement of molecules across a membrane.

Answer:

It needs carrier proteins.