Boss Fight: Antibiotic Resistance
IGCSE Biology 15.1.2 - Evolution by Natural Selection
Examiner Trap Alert:
Common mistake: Writing "bacteria become resistant" or "antibiotics make bacteria resistant." ✓ CORRECT: "Mutation produces resistance → antibiotic kills non-resistant → resistant survive and reproduce → allele frequency increases"
What is the PRIMARY cause of antibiotic resistance in bacteria?
A population of bacteria is exposed to an antibiotic. What happens to bacteria that do NOT have resistance?
Which statement BEST describes natural selection in antibiotic resistance?
MRSA (methicillin-resistant Staphylococcus aureus) is a bacterium resistant to many antibiotics. What is the MAIN factor that led to the development of MRSA?
Why should antibiotics NOT be used to treat viral infections like the common cold?
Natural Selection: The 5-Step Chain
- 1.Mutation occurs randomly in bacterial DNA producing resistance allele
- 2.Antibiotic kills non-resistant bacteria (selection pressure)
- 3.Resistant bacteria survive (selective advantage)
- 4.Reproduce and pass on resistance allele to offspring
- 5.Frequency of resistance allele increases in population = Evolution
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