Cells move polar molecules across the cell membrane against a concentration gradient using
A) energy and transport proteins.
B) simple diffusion.
C) modifications to membrane lipids.
D) random molecular movement.

Question

Quizplus · Accepted Answer

Polar molecules cannot diffuse easily across the cell membrane, and therefore require transport proteins for facilitated diffusion or active transport. Active transport requires the input of energy, which is typically in the form of ATP, to move molecules against a concentration gradient.

Cells Move Polar Molecules Across the Cell Membrane Against a Concentration