Which of these descriptions applies to the movement of molecules across the plasma membrane
A)If two similar molecules can both combine with the same carrier, the presence of one of these molecules increases the rate of entry of the other.
B)In simple diffusion, the rate of transport of a molecule is inversely proportional to the molecule's extracellular concentration.
C)When a carrier becomes saturated, the maximum rate of transport is reached.
D)Large molecules can cross it via nonselective, receptor-mediated endocytosis.

Question

Quizplus · Accepted Answer

When a carrier becomes saturated, the maximum rate of transport is reached. This means that as the concentration of the molecule being transported increases, the rate of transport will also increase until the carrier becomes saturated, at which point the maximum rate of transport is reached. Choices A and B are not entirely accurate as they do not apply to all types of movement across the plasma membrane, while choice D is only applicable to large molecules and not all molecules.

Which of These Descriptions Applies to the Movement of Molecules