When molecules move freely across the cell membrane down the concentration gradient, this is called:
A) facilitated diffusion.
B) carrier diffusion.
C) osmosis.
D) simple diffusion.
E) active transport.

Question

Quizplus · Accepted Answer

Simple diffusion is the process by which molecules move freely across the cell membrane down the concentration gradient. Facilitated diffusion requires the assistance of carrier proteins, osmosis refers specifically to the movement of water molecules, and active transport requires the expenditure of energy to move molecules against the concentration gradient.

When Molecules Move Freely Across the Cell Membrane Down the Concentration