Low-growing clover plants grow on a large green roof.
Students investigated the relationship between clover abundance and soil-surface temperature. They placed a gridded quadrat at six positions that were easy to reach. All six positions were within 5 m of the roof access door.
Their results, arranged in order of temperature, are shown in the table.
| Quadrat | Soil-surface temperature / ∘C^\circ\mathrm{C}∘C | Percentage cover of clover / % |
|---|---|---|
| A | 20.4 | 74 |
| B | 21.8 | 66 |
| C | 23.5 | 57 |
| D | 25.1 | 45 |
| E | 27.3 | 33 |
| F | 28.9 | 24 |
The students concluded that increasing soil-surface temperature causes the percentage cover of clover to decrease throughout the roof.
Evaluate the students' conclusion. In your answer, use the results and describe how further sampling could address limitations of the investigation.
82 exam-style questions on Edexcel GCSE Biology 9.1 Ecosystems and interdependence, covering 9.1.1 Levels of organisation in ecosystems, 9.1.2 Abiotic and biotic factors, 9.1.3 Importance of interdependence, 9.1.4 Parasitism and mutualism, and 9.1.5 Determining number of organisms in an area. Each one has a worked solution and a mark scheme showing where the marks go.