Diffusion and Concentration Gradients

“Diffusion is the net movement of particles from an area of high concentration to an area of low

concentration. This movement happens because particles move randomly. In cells,

diffusion allows oxygen to move into cells and carbon dioxide to move out,

down the concentration gradient. The process continues until the particles are evenly spread.

In exam questions, always explain the direction of movement using concentration gradient,

not just the word diffusion.”