Blackspot fungus on roses is sensitive to sulfur dioxide. No blackspot is found on roses beside a road. The roses have recently been sprayed with fungicide.
Which conclusion is justified?
High pollution is confirmed because the absence of blackspot rules out other causes.
Low pollution is confirmed because applying fungicide removes sulfur dioxide from the air.
Pollution cannot be inferred reliably because fungicide could explain the absence of blackspot.
Pollution can be inferred reliably because fungicide affects roses without affecting blackspot fungus.
44 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.