Question

6
which statement best describes the movement of materials across a cell membrane using active transport?
a. they move back and forth randomly between areas of different concentrations.
b. they move back and forth to keep both concentrations at zero.
c. they move from an area of lower concentration to an area of higher concentration.
d. they move from an area of higher concentration to an area of lower concentration.

Explanation:

Active transport is defined as the movement of substances across a cell membrane against their concentration gradient, which requires energy. This means substances move from an area of lower concentration to an area of higher concentration. Option A describes random movement (diffusion), B is incorrect as concentrations are not kept at zero, and D describes passive transport (down the gradient).

Answer:

C. They move from an area of lower concentration to an area of higher concentration.