Question

during diffusion, in which way do molecules move?
a molecules flow down the concentration gradient.
b molecules flow against the concentration gradient.
c from an area of low concentration to an area of high concentration.
d none of the above

Explanation:

Diffusion is the passive movement of molecules from an area of higher concentration to an area of lower concentration, which is down the concentration gradient. Option b is incorrect as moving against the gradient is active transport. Option c is incorrect as it describes movement opposite to diffusion. So option a is correct.

Answer:

a. Molecules flow down the concentration gradient.