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CAIE A-Level Biology A2 17.2.4 Antibiotic Resistance and Selection Questions

Practise separating the origin of resistance genes from antibiotic selection, then trace survival, reproduction and inheritance to a resistant bacterial population.

Syllabus
2028–2030
Course
Biology 9700
Level
A2

Exam points

  • Explain how random mutation and horizontal gene transfer introduce antibiotic-resistance genes into bacterial populations.
  • Trace antibiotic selection pressure through differential survival, reproduction and an increasing resistance-allele frequency.

CAIE A-Level Biology A2 17.2.4 Antibiotic Resistance and Selection Questions question 1

[Maximum number: 5]

Interferon-alpha (IFN- α\alpha ) can be produced as a recombinant human protein to treat some types of cancer. The gene IFNA2 codes for IFN- α\alpha.

One method of producing recombinant IFN- α\alpha uses genetically engineered Escherichia coli bacteria that contain recombinant plasmids. Each recombinant plasmid contains:
- the gene IFNA2
- three regulatory sequences of the lac operon (promoter, operator and lacl)
- a gene for antibiotic resistance, AMPRA M P^{R}.

Each of the sequences for the lacI gene and AMPRA M P^{R} gene contains its own promoter. As a result, these genes are always expressed in E. coli bacteria that contain this recombinant plasmid.

Fig. 2.1 is a diagram of the recombinant plasmid. The promoter regions of the lacI gene and AMPRA M P^{R} gene are not shown.

Fig. 2.1

Fig. 2.1

Bacteria can evolve antibiotic resistance through natural processes.
Outline how bacteria can evolve to become resistant to antibiotics.

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