The Table shows the surface area : volume ratio of three organisms. Each ratio was calculated using measurements in cm.
Table
| Organism | Surface area : volume ratio |
|---|---|
| Amoeba (single-celled) | 120:1120:1120:1 |
| mouse | 5:15:15:1 |
| human | 0.25:10.25:10.25:1 |
Calculate how many times greater the surface area : volume ratio of Amoeba is than the surface area : volume ratio of the mouse.
Explain why Amoeba can obtain all the oxygen it needs by diffusion across its cell membrane.
Explain why a human needs lungs and a transport system to supply oxygen to its cells.
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.