A horse is vaccinated against a disease caused by a bacterium. Several months later, the same live bacterium enters the horse's body.
Which option shows how the vaccination can stop the horse becoming ill?
Memory cells engulf the bacterium and digest it before antibodies are needed.
Antitoxins produced after vaccination lock onto the bacterium's antigens and destroy it.
Antigens from the vaccine remain in the blood and destroy the bacterium directly.
Memory cells recognise the antigens and quickly make many of the correct antibodies.
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.