Explain why it is important that people complete the full course of antibiotics prescribed by their doctor, even if they begin to feel better before the course is finished.

Eduqas GCSE Biology — 2.6.3 Medicines and drugs · Explain · 4 marks · View as Markdown

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

Model answer (4 marks)

Some bacteria may still be present when symptoms improve, so stopping early leaves them alive.
If the treatment is stopped, these surviving bacteria can multiply.
The bacteria that survive are often those that are resistant to the drug.
This increases the number of antibiotic‑resistant strains, making the antibiotic less effective later.

Examiner tips

  • Use the exact wording from the mark scheme (e.g., ‘surviving bacteria’, ‘antibiotic‑resistant strains’).
  • Show the causal chain: incomplete treatment → survival → multiplication → resistance.
  • Keep the answer concise – one sentence per point to hit all four marks.

Common mistakes

  • Using vague terms like ‘more bacteria’ instead of ‘surviving bacteria’.
  • Omitting the link between resistance and future ineffectiveness.

Mark scheme (4 marks)

  1. Some bacteria may still be present / not all bacteria are killed early in the course
  2. Stopping early allows surviving bacteria to reproduce / multiply
  3. Surviving bacteria may be those that are resistant to the antibiotic
  4. This leads to an increase in antibiotic-resistant strains / makes the antibiotic less effective in future

Key terms in this question

antibiotics

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