Gas exchange surfaces across different organisms are highly adapted to maximize diffusion. Fick's Law of Diffusion mathematically describes this relationship as follows:
Rate of diffusion∝Surface Area×Concentration DifferenceThickness of Membrane \text{Rate of diffusion} \propto \frac{\text{Surface Area} \times \text{Concentration Difference}}{\text{Thickness of Membrane}} Rate of diffusion∝Thickness of MembraneSurface Area×Concentration DifferenceDescribe how the structure of fish gills and the counter-current exchange mechanism maximize the rate of oxygen diffusion in accordance with Fick's Law.
Describe how the tracheal system of an active insect is adapted to maximize the rate of gas diffusion.
16 exam-style questions on Edexcel IGCSE Biology Gas exchange. Each one has a worked solution and a mark scheme showing where the marks go.