The rate of diffusion through a selectively permeable membrane will be lowest when which of the following is(are) true? I.
Concentration gradients are steep.
II)
Temperatures are low.
III)
Solutes are small molecules.
A) I only
B) II only
C) I and III
D) II and III
E) I, II, and III

Question

Quizplus · Accepted Answer

According to Fick's Law of Diffusion, the rate of diffusion is directly proportional to the concentration gradient and the permeability of the membrane, and inversely proportional to the thickness of the membrane and the molecular weight of the solute. Therefore, option I suggests that concentration gradients are steep, which would increase the rate of diffusion, and option III suggests that the solutes are small molecules, which would also increase the rate of diffusion. However, option II suggests that temperatures are low, which would decrease the rate of diffusion. Therefore, the best choice is B, II only, as low temperatures would slow down the rate of diffusion through the membrane.

The Rate of Diffusion Through a Selectively Permeable Membrane Will