Scientists studied green-roof plots containing a tall grass and a low-growing flowering plant. The two plant species compete with each other.
Hoverflies feed on nectar from the low-growing plant and pollinate its flowers.
The scientists removed all the tall grass from half of the plots. The plots began with similar numbers of low-growing plants. The table shows the mean results.
| Measurement | Tall grass present | Tall grass removed |
|---|---|---|
| Light reaching the leaves of the low-growing plant as a percentage of full daylight | 31 | 74 |
| Number of flowering low-growing plants per m² | 14 | 29 |
| Number of hoverfly visits per m² in 10 minutes | 5 | 13 |
| Number of low-growing plant seedlings per m² the following spring | 8 | 25 |
Explain the differences between the results for the plots with tall grass present and the plots with tall grass removed.
In a later year, tall grass was present in every plot. A new predatory spider entered some of the plots and ate many hoverflies.
Suggest how the numbers of low-growing plant seedlings and tall grass plants in these plots would differ from plots without the new spider.
82 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.