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 molecular movement is limited by the number of available carrier molecules.
D)facilitated diffusion never eliminates the concentration gradient.
E)the rate of molecular movement is not limited by the number of available carrier molecules.

Question

Quizplus · Accepted Answer

Facilitated diffusion is a type of passive transport that moves molecules from an area of higher concentration to an area of lower concentration, but it requires the help of transporter proteins to cross the plasma membrane. The rate of facilitated diffusion is limited by the number of available transporter proteins or carrier molecules, which can become saturated when all binding sites are occupied. Therefore, the rate of facilitated diffusion is not unlimited and can be influenced by factors such as the concentration gradient, the affinity of the carrier protein for the solute, and the number of available carriers. Unlike active transport, facilitated diffusion does not consume ATP and cannot move molecules against their concentration gradient (i.e., from low to high concentration).

Facilitated Diffusion Differs from Ordinary Diffusion in That