A botanical reserve is near a volcanic vent that releases sulfur dioxide.
Scientists investigated four sites at different distances from the vent. At each site, they:
The table shows their results.
| Site | Distance from vent in km | Sulfur dioxide concentration in µg per m³ | Sensitive lichen species on tree 1 | Sensitive lichen species on tree 2 | Sensitive lichen species on tree 3 | Rose plants infected with blackspot out of 10 |
|---|---|---|---|---|---|---|
| A | 0.5 | 60 | 1 | 2 | 3 | 0 |
| B | 1.5 | 36 | 4 | 5 | 6 | 2 |
| C | 3.0 | 14 | 9 | 10 | 11 | 8 |
| D | 5.0 | 8 | 3 | 12 | 4 | 2 |
Calculate the percentage increase in the mean number of sensitive lichen species per tree from site A to site C.
Explain why the low sulfur dioxide reading at site D does not necessarily mean that many rose plants at this site will have blackspot.
Evaluate the scientists' conclusion that air quality improves continuously as distance from the volcanic vent increases.
101 exam-style questions on Edexcel GCSE Biology 9.3 Material cycles and decomposition, covering 9.3.1 Cycling of materials through ecosystems, 9.3.2 The carbon cycle, 9.3.3 The water cycle, 9.3.4 The nitrogen cycle, 9.3.5 Indicator species and pollution, 9.3.6 Decomposition in preservation and composting, and 9.3.7 Rate changes in decay of biological material. Each one has a worked solution and a mark scheme showing where the marks go.