Lichens grow on trees and walls. Some species of lichen cannot survive where there is a high concentration of sulfur dioxide in the air.
Scientists recorded the number of lichen species and the concentration of sulfur dioxide at sites at different distances from a city centre.
The Table shows the results.
Table
| Distance from city centre in km\text{km}km | Mean concentration of sulfur dioxide in μg/m3\mu\text{g}/\text{m}^3μg/m3 | Number of lichen species |
|---|---|---|
| 0 | 120 | 1 |
| 2 | 95 | 2 |
| 4 | 70 | 5 |
| 6 | 40 | 9 |
| 8 | 25 | 14 |
| 10 | 20 | 16 |
Describe the relationship between the concentration of sulfur dioxide and the number of lichen species.
Use data from the Table in your answer.
Calculate the mean decrease in the concentration of sulfur dioxide per km\text{km}km between 0 km and 8 km.
Give your answer to 3 significant figures.
A student concludes:
'Sulfur dioxide is the only factor that affects the distribution of lichens around this city.'
Evaluate the student's conclusion.
The concentration of sulfur dioxide in the air of UK cities has fallen a lot since 1970.
Predict and explain how the distribution of lichen species near city centres has changed.
109 exam-style questions on OCR GCSE Biology 6.1 Monitoring and maintaining the environment, covering 6.1.1 Field investigation of distribution and abundance, 6.1.2 Human interactions and biodiversity, 6.1.3 Maintaining biodiversity, and 6.1.4 Environmental change and distribution of organisms. Each one has a worked solution and a mark scheme showing where the marks go.