Question

question 3
which of the following statements about diffusion is correct?
it is very rapid over long distances.
it requires an expenditure of energy by the cell.
it is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.
it is an active process in which molecules move from a region of lower concentration to one of higher concentration.
it is a passive process in which molecules move from a region of lower concentration to a region of higher concentration.

Explanation:

Diffusion is a passive process (no energy expenditure). Molecules move down the concentration gradient (higher to lower). It's slow over long distances. Active transport (opposite of diffusion) requires energy and moves molecules against the gradient (lower to higher).

Answer:

It is a passive process in which molecules move from a region of higher concentration to a region of lower concentration.