A scientist compared equal numbers of two cell types that absorb a dissolved substance, T. The concentration of T was 0.50 mmol dm-3 outside both cell types and 4.0 mmol dm-3 inside both cell types. Both cell types had the same number of carrier proteins per μm2\mu\text{m}^2μm2 of cell membrane.
| Cell type | Mean cell-membrane surface area in μm2\mu\text{m}^2μm2 | Mean number of mitochondria per cell | Rate of uptake of T in nmol per minute per million cells |
|---|---|---|---|
| P | 800 | 120 | 6.0 |
| Q | 400 | 40 | 2.0 |
Explain why cell type P had a higher rate of uptake of substance T than cell type Q. Use information from the table.
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.