Lichens are organisms that are sensitive to acidic gases in the air.
A survey found that one species of lichen was absent from a city centre but was present 10 km from the city centre.
Which is the most valid conclusion from this survey?
Acidic gases from the city have killed every species of lichen within 10 km of the centre
The distribution of this lichen is consistent with higher air pollution near the city centre
The lichen has moved away from the city centre to avoid the acidic gases in the air there
The lichen needs more light, and tall buildings in the city centre prevent it from growing
49 exam-style questions on AQA GCSE Biology 7.3 Biodiversity and the effect of human interaction on ecosystems, covering 7.3.1 Biodiversity, 7.3.2 Waste management, 7.3.3 Land use, 7.3.4 Deforestation, 7.3.5 Global warming, and 7.3.6 Maintaining biodiversity. Each one has a worked solution and a mark scheme showing where the marks go.