Table of Contents Diffusion Defination Diffusion is the net movement of molecules and ions from a region of their higher concentration to a region of their lower concentration down a concentration gradient, as a result of their random movement. What is Diffusion  The molecules of a gas such as oxygen are moving about all the time. So are the molecules of a liquid or a substance such as sugar dissolved in water. As a result of this movement, the molecules spread themselves out evenly to fill all the available space (Figure). Diffusion This process is called diffusion. How are substances transported by diffusion? One effect of diffusion is that the…