When materials diffuse across a membrane, they move from of concentration to an area of concentration along the concentration gradient.

When materials diffuse across a membrane, they move from an HIGHER area of concentration to a LOWER area of concentration along the concentration gradient.

Explanation:

A concentration gradient is the process where particles, also called solutes, move through a solution or gas from an area (usually separated by a membrane) with a higher number of particles to an area with a lower number of particles, in other words, from a higher concentration area to a lower concentration until the concentration of substances is uniform throughout.

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explanation: