Two developing animal embryos live in water. Oxygen enters each embryo by diffusion across its permeable outer exchange surface. The embryos are at the same temperature and have the same oxygen requirement per mm3\mathrm{mm^3}mm3 of tissue.
The measurements are shown in the table.
| Embryo | Surface area in mm2\mathrm{mm^2}mm2 | Oxygen concentration difference in mg dm−3\mathrm{mg\,dm^{-3}}mgdm−3 | Thickness of exchange surface in mm\mathrm{mm}mm | Volume in mm3\mathrm{mm^3}mm3 |
|---|---|---|---|---|
| R | 24 | 5.0 | 0.010 | 8.0 |
| S | 36 | 6.0 | 0.015 | 18.0 |
Calculate a relative oxygen supply value per mm3\mathrm{mm^3}mm3 of tissue for each embryo. Explain which embryo is predicted to be better able to meet the oxygen requirement of its tissue.
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.