What is diffusion? Provide an example of this process in a biological system.

Diffusion refers to the process where particles (molecules and ions) move from an area of high concentration to an area of lower concentration. I would draw a diagram of the process and make it clear that particles will continue to move in both directions, but there is a net movement from high to low concentration. I would explain that diffusion happens because of the random movement of individual particles.
Biological examples could include:1) In the lungs2) In liver cells3) In a leaf