Two artificial exchange surfaces are kept under the same conditions. Their measurements are shown in the table.
| Exchange surface | Surface area (cm²) | Concentration difference (mmol dm⁻³) | Membrane thickness (mm) |
|---|---|---|---|
| R | 40 | 6 | 0.20 |
| S | 60 | 6 | 0.30 |
Using Fick's law, calculate the relative diffusion value for each exchange surface and explain how the rates of diffusion across the two surfaces compare.
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.