Two multicellular aquatic worm species take in oxygen by diffusion across their outer body surfaces. Their cells use oxygen at the same rate per unit volume of tissue.
| Species | Surface area in mm2\mathrm{mm^2}mm2 | Volume in mm3\mathrm{mm^3}mm3 | Greatest distance of a cell from the body surface in mm\mathrm{mm}mm |
|---|---|---|---|
| R | 240 | 80 | 0.3 |
| S | 630 | 420 | 1.1 |
Calculate the surface area to volume ratio for each species. State which species is more likely to supply oxygen rapidly to all its cells by diffusion across its outer surface. Explain your answer using the data.
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.