Facilitated diffusion differs from ordinary diffusion in that
A) facilitated diffusion consumes ATP.
B) facilitated diffusion moves molecules from an area of lower concentration to an area of higher concentration.
C) the rate of facilitated diffusion is limited by the number of available carrier proteins.
D) facilitated diffusion never eliminates the concentration gradient.
E) facilitated diffusion does not rely on carrier proteins.

Question

Quizplus · Accepted Answer

Facilitated diffusion requires carrier proteins to move molecules across the membrane. Therefore, the rate of facilitated diffusion is limited by the number of available carrier proteins. This is different from ordinary diffusion, which does not require carrier proteins and depends only on the concentration gradient. The other options are incorrect: A) facilitated diffusion does not consume ATP, B) facilitated diffusion always moves molecules from an area of higher concentration to an area of lower concentration, D) facilitated diffusion can eliminate the concentration gradient, and E) facilitated diffusion relies on carrier proteins.

Facilitated Diffusion Differs from Ordinary Diffusion in That