Disease X is a communicable disease of humans caused by a bacterium. Scientists recorded the number of people with disease X in four villages. The table shows their results.
Table: The number of people with disease X per 1000 people in four villages, and the source of drinking water used in each village
| Village | Source of drinking water | Number of people with disease X per 1000 people |
|---|---|---|
| P | river, untreated | 84 |
| Q | river, treated with chlorine | 12 |
| R | deep well, untreated | 9 |
| S | river, untreated | 91 |
Give one conclusion about how disease X is spread that can be made from the data in the table.
The scientists recorded the number of people with disease X per 1000 people rather than the total number of people with disease X in each village. Explain why.
Suggest two ways, other than treating the drinking water, that the number of new cases of disease X in village S could be reduced.
A doctor concludes that drinking untreated river water causes disease X. Explain why the doctor cannot be certain that this conclusion is correct.
176 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.