Seedlings are grown either alone or with grass. The table shows their mean increase in mass.
| Treatment | Seedlings alone / g | Seedlings with grass / g |
|---|---|---|
| No extra resources | 8 | 3 |
| Extra water only | 8 | 7 |
| Extra mineral ions only | 8 | 3 |
Light intensity, soil volume and temperature are the same in every treatment.
Which conclusion is best supported by both comparisons?
Grass mainly limits mineral ions; adding water removes competition for minerals.
Grass mainly limits water supply; adding minerals leaves this competition unchanged.
Grass mainly limits light intensity; adding minerals leaves this competition unchanged.
Grass mainly limits growing space; adding water removes competition for space.
40 exam-style questions on AQA GCSE Biology 7.1 Adaptations, interdependence and competition, covering 7.1.1 Communities, 7.1.2 Abiotic factors, 7.1.3 Biotic factors, and 7.1.4 Adaptations. Each one has a worked solution and a mark scheme showing where the marks go.