DP Biology (first assessment 2025)

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Question 20N.1B.SL.TZ0.a

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Date November 2020 Marks available [Maximum mark: 2] Reference code 20N.1B.SL.TZ0.a
Level SL Paper 1B Time zone TZ0
Command term Describe Question number a Adapted from N/A
a.
[Maximum mark: 2]
20N.1B.SL.TZ0.a

Describe the control for this experiment.

[2]

Markscheme

a. same apparatus with carbon dioxide present;

b. (control has) no sodium hydroxide/alkali;

c. control irrigated with untreated water/water with CO2;

“Same apparatus” alone does not get the mark.

Examiners report

Many candidates had difficulty describing the control for this experiment. The question states that the experiment was to investigate whether carbon dioxide is required for photosynthesis therefore it seems straightforward that the plant would be in similar conditions with and without carbon dioxide. Some candidates assumed that the control plant would have similar conditions and no light.

Syllabus sections