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A Levels Biology (9700)•9700/11/O/N/19
Question 37 from 9700/11/O/N/19

Explanation

Antibiotic Rotation to Combat Resistance

Steps:

  • Identify the goal: Reduce bacterial resistance by minimizing selective pressure on populations.
  • Evaluate each option: Check if it limits exposure that allows resistant strains to survive and spread.
  • Consider resistance mechanisms: Bacteria evolve resistance through mutations or gene transfer under antibiotic stress.
  • Select the strategy: Choose the one that diversifies pressure to prevent dominance of any single resistant type.

Why C is correct:

  • Rotating antibiotics disrupts adaptation by exposing bacteria to varying drugs, preventing widespread resistance as per evolutionary principles of selective pressure.

Why the others are wrong:

  • A: High concentrations can kill most bacteria but survivors are highly resistant, accelerating spread.
  • B: Routine prophylaxis increases unnecessary exposure, promoting resistance in non-infected populations.
  • D: Treating low-level infections uses sub-lethal doses, allowing partial survival and resistance selection.

Final answer: C

Topic: Antibiotics

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