In facilitated diffusion, the diffusion rate of a specific molecule across a membrane does not continue to increase as the molecule's concentration difference across the membrane increases beyond a certain point.The reason is that
A) facilitated diffusion requires the use of ATP.
B) as the concentration difference increases, molecules interfere with one another.
C) the carrier proteins become saturated.
D) the transport protein is a channel protein.
E) the diffusion constant depends on the concentration difference.

Question

Quizplus · Accepted Answer

In facilitated diffusion, molecules are transported across the membrane with the help of specific carrier proteins. However, these carrier proteins have a limited capacity, which means that they can transport only a certain number of molecules at a time. When the concentration difference across the membrane becomes too high, all of the carrier proteins become saturated and are unable to transport any additional molecules. This results in a plateau in the diffusion rate, even if the concentration difference continues to increase.

In Facilitated Diffusion, the Diffusion Rate of a Specific Molecule