A multicellular animal has two exchange surfaces where oxygen enters the blood. A student measured the membrane thickness and the rate of oxygen uptake at each surface. The two surfaces had the same surface area, temperature and difference in oxygen concentration.
| Exchange surface | Membrane thickness | Oxygen uptake rate |
|---|---|---|
| X | 1.5 μm | 72 μmol per minute |
| Y | 4.5 μm | 25 μmol per minute |
Use the data in the table to explain the difference in oxygen uptake rate between surfaces X and Y.
The membrane at surface X then becomes 4.5 μm thick, with all other conditions unchanged. Predict the oxygen uptake rate at surface X. Give a reason for your prediction.
140 exam-style questions on AQA GCSE Biology 1.3 Transport in cells, covering 1.3.1 Diffusion, 1.3.2 Osmosis, and 1.3.3 Active transport. Each one has a worked solution and a mark scheme showing where the marks go.