A researcher compares the diffusion rates across two exchange surfaces.
| Exchange surface | Surface area (mm²) | Concentration difference (mmol dm⁻³) | Membrane thickness (mm) |
|---|---|---|---|
| A | 30 | 6.0 | 0.20 |
| B | 45 | 4.0 | 0.30 |
Temperature and all other factors affecting diffusion are the same for both surfaces.
Using Fick's law, calculate the diffusion rate across surface B relative to surface A.
102 exam-style questions on Edexcel GCSE Biology 8.1 Exchange surfaces and diffusion, covering 8.1.1 Introduction to exchange and transport, 8.1.2 Alveoli adapted for gas exchange, 8.1.3 Factors affecting rate of diffusion, and 8.1.4 Rate of diffusion using Fick's law. Each one has a worked solution and a mark scheme showing where the marks go.