Diffusion is important to cells because it allows them to gain the useful substances they require to obtain energy and grow, and lets them get rid of waste products.
This table shows examples of substances required by cell and associated waste products.
|Substance required by cell||Waste product of cell|
|Oxygen||Urea (made from excess amino acids)|
The diagram below shows the differences in the concentrations of some of these substances between a cell and its environment and the direction that they diffuse.