Give three features of an efficient exchange surface. Provide an example for each feature.

An efficient exchange surface should have a high surface area as this increases the rate at which diffusion can occur across it. For instance, roots have many root hair cells. These root hair cells have thin protrusions called root hairs. The presence of millions of these root hairs increases the surface area of the exchange surface massively.An efficient exchange surface should be thin. This reduces the diffusion distance and so increases the rate of diffusion across the surface. For instance, alveoli are one cell thick.An efficient exchange surface should maintain the concentration gradient of the substance that is being exchanged. This keeps the gradient high and so keeps diffusion rates high. This is achieved in mammalian gaseous exchange systems via constant ventilation and good blood supply.