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Lichen species grow on trees and are air quality indicators - Edexcel - GCSE Biology - Question 5 - 2013 - Paper 1
Question 5
Lichen species grow on trees and are air quality indicators. The table shows the sulfur dioxide concentrations in three areas (A, B and C). Each area contained 100... show full transcript
Worked Solution & Example Answer:Lichen species grow on trees and are air quality indicators - Edexcel - GCSE Biology - Question 5 - 2013 - Paper 1
Step 1
Calculate the difference in the number of trees in area A and area C with lichen growing on them.
Answer
To find the difference in the number of trees with lichen in area A (204 trees) and area C (14 trees), we subtract the number of trees in area C from area A:
Substituting the values:
Therefore, the difference in the number of trees in area A and area C with lichen growing on them is 190.
Step 2
Describe the effect of sulfur dioxide on the number of lichen.
Answer
An increase in sulfur dioxide concentration tends to decrease the number of lichen species present. This can be observed by analyzing the data:
- In area A with a sulfur dioxide concentration of 5 ppm, there are 204 trees with lichen.
- In area B with a concentration of 1 ppm, there are 437 trees with lichen.
- In contrast, area C, with the highest sulfur dioxide concentration of 15 ppm, has only 14 trees with lichen.
This suggests a clear negative correlation between sulfur dioxide levels and the lichen population, indicating that higher sulfur dioxide concentrations adversely affect lichen growth.