Explain how vaccination protects a person from becoming seriously ill when they are later infected by a pathogen.

Eduqas GCSE Biology — 3.3 Treating, curing and preventing disease · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

1. The vaccine contains a weakened, dead or harmless form of the pathogen (or its antigens).
2. The immune system produces antibodies in response to the antigens in the vaccine.
3. Memory cells are produced that remain in the body long‑term.
4. On re‑exposure to the same pathogen, memory cells allow a faster/greater antibody response so the pathogen is destroyed before serious illness develops.

Examiner tips

Use the exact terminology: "antigens", "antibodies", "memory cells". Show the causal chain: vaccine → immune response → memory → rapid response on infection. Keep each point concise and separate with numbers or bullets.

Common mistakes

Mixing up the order of the steps. Using vague terms like "immune system" without specifying antibodies or memory cells. Forgetting to mention that the vaccine contains a weakened or dead form of the pathogen.

Mark scheme (4 marks)

The vaccine contains a weakened, dead or harmless form of the pathogen (or its antigens)
The immune system produces antibodies in response to the antigens in the vaccine
Memory cells are produced that remain in the body long-term
On re-exposure to the same pathogen, memory cells allow a faster/greater antibody response so the pathogen is destroyed before serious illness develops

Key terms in this question

vaccination · pathogen

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