A viral disease spreads by direct contact between dogs at a rehoming centre. Most of the dogs are vaccinated against the virus, but one dog cannot be vaccinated. How does vaccinating most of the dogs protect the dog that cannot be vaccinated?
The unvaccinated dog develops memory cells by being in contact with dogs that have been vaccinated
Vaccinated dogs interrupt chains of transmission, reducing the chance that the virus reaches the unvaccinated dog
The vaccinated dogs are less likely to show symptoms, so the unvaccinated dog is less likely to become ill
The virus becomes inactive after entering a vaccinated dog, so it is harmless if it reaches the unvaccinated dog
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.