Question

which phrase best defines diffusion?
movement of water particles from an area of low concentration to an area of high concentration
movement through a cell membrane using energy from atp
movement of particles up a concentration gradient with the help of proteins
movement of particles from an area of high concentration to an area of low concentration

Explanation:

Diffusion is the passive movement of particles down a concentration gradient, from an area of high particle - concentration to an area of low particle - concentration. The first option describes osmosis (water movement against the typical diffusion direction), the second is active transport, and the third is facilitated diffusion (but against the normal diffusion gradient direction).

Answer:

movement of particles from an area of high concentration to an area of low concentration