A small animal hatches in water. Oxygen diffuses from the water through its outer surface. As the animal grows, it keeps the same overall body shape and its cells remain approximately the same size.
| Stage | Outer surface area in cm² | Volume in cm³ | Greatest distance from the outer surface to a cell in cm |
|---|---|---|---|
| Newly hatched | 18 | 3 | 0.25 |
| Adult | 288 | 192 | 1.00 |
Use the data to explain why the adult needs specialised exchange surfaces and a transport system to supply its cells with oxygen.
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.