A-Level Biology May/June 2025 Q3(d)(ii): Some strains of S. aureus are resistant to vancomycin and penicillin. Describe the step…

1 answer

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  To reduce the impact of antibiotic resistance, several measures can be implemented:

  1. Restrict the use of antibiotics: Antibiotics should only be prescribed by doctors when absolutely necessary, and not for viral infections like the common cold, as they are ineffective against viruses. This reduces the selection pressure on bacterial populations.

  2. Ensure patients complete the full course: Patients must be educated to complete the entire prescribed course of antibiotics, even if they start to feel better. This ensures that all the pathogenic bacteria are killed, preventing the survival and proliferation of more resistant individuals.

  3. Control antibiotic use in agriculture: The routine use of antibiotics in livestock farming, for example as growth promoters, should be reduced or stopped. This practice contributes significantly to the environmental reservoir of resistant bacteria and resistance genes.

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  How the marks are awarded

  • B1 — The first point correctly states that antibiotics should only be prescribed when necessary and not for viral infections, which directly matches a marking point.
  • B1 — The second point earns a mark for stating that patients must complete the full course of antibiotics, a key strategy to prevent the selection of resistant bacteria.
  • B1 — The third point identifies the need to reduce or control the use of antibiotics in agriculture/animals, which is another distinct and valid measure.

  Common mistakes

  • Stating that humans or animals become resistant to antibiotics, rather than the bacteria themselves.
  • Giving vague answers like 'use less medicine' without specifying antibiotics and the context (e.g., for viral infections, in agriculture).
  • Incorrectly suggesting that patients should stop taking antibiotics as soon as their symptoms disappear, which actually increases the risk of resistance.
  • Failing to mention non-medical contexts, such as the widespread use of antibiotics in agriculture, which is a major contributor to the problem.

  Examiner tip: For questions asking for 'steps' or 'ways', structure your answer as a clear, numbered or bulleted list to ensure you provide distinct, mark-worthy points.

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