Two identical membranes separate solutions of the same solute. Temperature is constant. The concentrations are shown in the table.
Table
| Membrane | Left concentration in mmol dm−3\mathrm{mmol\,dm^{-3}}mmoldm−3 | Right concentration in mmol dm−3\mathrm{mmol\,dm^{-3}}mmoldm−3 |
|---|---|---|
| P | 14 | 8 |
| Q | 9 | 1 |
Which statement compares the initial net diffusion rates from left to right?
Q is faster because the concentration difference is greater across Q.
P is faster because the concentration on the left is greater for P.
P is faster because the concentration on the right is greater for P.
Both are equal because the membranes have the same physical dimensions.
42 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.