A student investigated the uptake of magnesium ions by cells taken from an aquatic plant.
The concentrations at the start of the investigation are shown in the table.
| Location | Magnesium ion concentration in mmol/dm³ |
|---|---|
| Solution outside the cells | 0.15 |
| Inside the cells | 1.20 |
The student measured magnesium ion uptake under two conditions.
| Condition | Magnesium ion uptake in µmol per gram per hour |
|---|---|
| No chemical added | 5.0 |
| Chemical that reduces the rate of respiration added | 2.0 |
Calculate the percentage decrease in magnesium ion uptake when the chemical was added.
Using the concentration data and your answer to part (a), explain which process moves magnesium ions into the cells.
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.