A botanist uses this expression to model carbon dioxide diffusion across a photosynthesising leaf surface.
relative diffusion value=surface area×concentration differencemembrane thickness \text{relative diffusion value}=\frac{\text{surface area}\times\text{concentration difference}}{\text{membrane thickness}} relative diffusion value=membrane thicknesssurface area×concentration difference| Measurement | Value |
|---|---|
| Relative diffusion value | 36 units |
| Surface area | 12 units |
| Membrane thickness | 2 units |
What is the concentration difference?
666 units
727272 units
181818 units
333 units
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.