Surface Area to Volume Ratio¶

Use this interactive to compare surface area, volume and the SA:V ratio in one cube model. It is most useful for seeing why multicellular organisms cannot rely on exchange across the outer body surface alone once size increases.

This model treats diffusion as reaching a fixed depth from each surface, so the shaded core is a teaching device for "too far from the surface in the same time window", not a literal dead centre in a real organism.

Connected Pages¶

• 3.1.1 Exchange Surfaces
• 3.1.2 Transport in animals
• 3.1.3 Transport in plants