Scientists investigated whether living near a motorway is a risk factor for asthma in children. They compared 200 children living within 100 m of a motorway with 200 children living in a village 20 km away.
Suggest two factors, other than where the children lived, that the scientists should have matched between the two groups.
The scientists found that 18 % of the motorway group and 7 % of the village group had asthma. Explain why this result does not prove that traffic pollution causes asthma in children.
Suggest one type of evidence that would show that traffic pollution does cause asthma.
179 exam-style questions on AQA GCSE Biology 2.2 Animal tissues, organs and organ systems, covering 2.2.1 The human digestive system, 2.2.2 The heart and blood vessels, 2.2.3 Blood, 2.2.4 Coronary heart disease: a non-communicable disease, 2.2.5 Health issues, 2.2.6 The effect of lifestyle on some non-communicable diseases, and 2.2.7 Cancer. Each one has a worked solution and a mark scheme showing where the marks go.