DP Biology (first assessment 2025)

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Question 23M.2.HL.TZ1.c

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Date May 2023 Marks available [Maximum mark: 4] Reference code 23M.2.HL.TZ1.c
Level HL Paper 2 Time zone TZ1
Command term Explain Question number c Adapted from N/A
c.
[Maximum mark: 4]
23M.2.HL.TZ1.c

Explain the effects that the environment can have on DNA in living organisms.

[4]

Markscheme

Mutation

a. (environment can cause) mutation;
b. mutations are base sequence changes;
c. radiation/UV/gamma rays can cause mutations/changes to base sequences;
d. mutagenic/carcinogenic chemicals can cause mutations / mustard gas/another example;

Epigenetics

e. (environment) can cause changes to gene expression;
f. methylation (patterns) in DNA changed (in response to environmental factors);
g. methylation inhibits (gene transcription) / acetylation promotes (gene transcription);
h. body temperature/stress/diet (can affect gene expression);

For mpd do not allow ‘mutagen’ instead of ‘mutagenic chemical’ as it includes forms of radiation as well as chemicals.

Allow smoking and asbestos as examples of mutagens /carcinogens in mpd.

Syllabus sections