DP Biology (first assessment 2025)

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Question 23M.2.HL.TZ1.3bii

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

Antibiotics such as penicillin are secreted by fungi and other microorganisms in soil. By secreting them, a microorganism can inhibit the growth of a competitor.

In research published in 2014, nearly 3000 antibiotic resistance genes were discovered in soil microorganisms, giving resistance to 18 different antibiotics. The types of antibiotic resistance gene varied between soil types.

(ii)

Explain the reasons for antibiotics secreted into soil not harming insects or other animals in the soil.

[2]

Markscheme
  1. antibiotics (only) affect/kill/block processes in bacteria/prokaryotes / do not affect eukaryotes;
  2. metabolism/protein synthesis/ribosomes/cell walls not targeted in insects/animals/eukaryotes;
  3. no cell walls in animals (so antibiotics cannot attack cell walls);
  4. antibiotics are secreted (by microbes/fungi) to prevent competition (with other microbes);

 

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