The transport of substances across a cell membrane with the aid of a carrier molecule and the expenditure of energy is
A) active transport.
B) facilitated diffusion.
C) osmosis.
D) simple diffusion.

Question

Quizplus · Accepted Answer

Active transport refers to the movement of substances across the cell membrane against their concentration gradient, from an area of low concentration to an area of high concentration, with the aid of a carrier molecule and the expenditure of energy in the form of ATP.

The Transport of Substances Across a Cell Membrane with the Aid