In a valley, all the people diagnosed with malaria were treated with an antimalarial drug until blood tests found no malaria protists. The number of mosquitoes in the valley did not change. Over the next few months, the number of new malaria cases fell. What is the best explanation for this?
The drug made mosquitoes stop biting the treated people, so there were fewer bites
Malaria spreads in droplets, so curing patients reduced the protists released in coughs
The treated people could no longer pass protists to others by direct contact
With fewer protists in human blood, fewer mosquitoes acquired and transmitted the pathogen
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.