Question
Explain how a population of bacteria can become resistant to an antibiotic. [4 marks]
Mark scheme (1 mark each, max 4):
- Random mutation in bacterial DNA produces a (resistance) allele/variation
- Antibiotic acts as a selection pressure / kills non-resistant bacteria
- Resistant bacteria survive and reproduce (asexually / by binary fission)
- Resistance allele passed to offspring / frequency of resistance allele increases in population
- Over many generations the whole population becomes resistant
Must reference random mutation for full credit; 'bacteria evolve to become resistant' alone = 0 marks (Lamarckian).
4 marks · take your time before peeking.
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Generated by TopMyGrade AI · cross-check official sources before relying on the mark-scheme phrasing.