A gardener read that adding a fertiliser containing potassium ions to the soil makes plants grow faster.
The gardener grew 20 tomato plants in identical pots of the same soil. Ten plants were given the fertiliser and ten were not. After 8 weeks the gardener measured the height of every plant.
Table: The mean height and the range of heights of tomato plants after 8 weeks, with and without potassium fertiliser
| Treatment | Mean height in cm | Range of heights in cm |
|---|---|---|
| With fertiliser | 62 | 54 to 71 |
| Without fertiliser | 48 | 30 to 66 |
Calculate the percentage increase in the mean height of the plants given the fertiliser.
Explain how the potassium ions in the fertiliser get from the soil into the root hair cells.
The gardener concluded that the fertiliser makes tomato plants grow faster.
Evaluate the strength of the evidence for this conclusion.
Adding too much fertiliser can make the soil water more concentrated than the cytoplasm of the root hair cells.
Suggest why this damages the plant.
58 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.