Scientists tested an insecticide as a way of controlling mosquitoes in a region where malaria is common. They placed 50 mosquitoes into each of 20 enclosed spaces. Ten spaces had been sprayed with the insecticide and ten had not. After 12 hours, the mean number of living mosquitoes per space was 8 for the sprayed spaces and 42 for the unsprayed spaces. Which conclusion about the insecticide is supported by these results?
The insecticide stopped the 8 surviving mosquitoes from spreading malaria.
The mean number of living mosquitoes was 42 lower in sprayed spaces than in unsprayed spaces.
The insecticide reduced the mean number of mosquitoes alive after 12 hours.
The insecticide killed all 50 mosquitoes in every sprayed space.
252 exam-style questions on AQA GCSE Biology 3.1 Communicable diseases, covering 3.1.1 Communicable (infectious) diseases, 3.1.2 Viral diseases, 3.1.3 Bacterial diseases, 3.1.4 Fungal diseases, 3.1.5 Protist diseases, 3.1.6 Human defence systems, 3.1.7 Vaccination, 3.1.8 Antibiotics and painkillers, and 3.1.9 Discovery and development of drugs. Each one has a worked solution and a mark scheme showing where the marks go.