DP Biology (first assessment 2025)

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Question 23M.2.HL.TZ1.a

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Date May 2023 Marks available [Maximum mark: 3] Reference code 23M.2.HL.TZ1.a
Level HL Paper 2 Time zone TZ1
Command term Explain Question number a Adapted from N/A
a.
[Maximum mark: 3]
23M.2.HL.TZ1.a

Explain how natural selection could increase the prevalence of an antibiotic resistance gene in a species of soil bacterium.

[3]

Markscheme
  1. if antibiotic is in the environment/soil there is selection (pressure);
  2. bacteria without resistance (gene) die / converse;
  3. bacteria with resistance (gene) reproduce
    OR
    bacteria exchange/obtain resistance genes using plasmids/by conjugation;
  4. offspring inherit (the gene for) resistance/resistance passed on (to offspring);

Do not award marks for general statements about natural selection – answers must refer to antibiotic resistance.

Syllabus sections