A student investigates the uptake of potassium ions by plant roots.
The roots are kept in solutions with different concentrations of oxygen.
The table shows the results.
Table
| Oxygen concentration in %\%% | Rate of potassium ion uptake in arbitrary units |
|---|---|
| 0 | 2 |
| 5 | 12 |
| 10 | 20 |
| 20 | 21 |
Which statement explains the results?
Uptake is by active transport, which needs energy from aerobic respiration.
Uptake is by diffusion, which is faster when more oxygen is dissolved.
Uptake is by osmosis, which needs oxygen to make the membrane permeable.
Uptake is by active transport, which uses oxygen to carry the ions inwards.
114 exam-style questions on OCR GCSE Biology 2.2 The challenges of size, covering 2.2.1 Exchange surfaces and surface area : volume ratio, 2.2.2 Substances transported in organisms, 2.2.3 The human circulatory system, 2.2.4 The heart and blood vessels, 2.2.5 Red blood cells and plasma, 2.2.6 Uptake of water and mineral ions by plants, 2.2.7 Transpiration and translocation, 2.2.8 Xylem and phloem, 2.2.9 Environmental factors and water uptake, and 2.2.10 Using a potometer. Each one has a worked solution and a mark scheme showing where the marks go.