DP Biology (first assessment 2025)

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Question 21M.1A.SL.TZ2.19

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Date May 2021 Marks available [Maximum mark: 1] Reference code 21M.1A.SL.TZ2.19
Level SL Paper 1A Time zone TZ2
Command term Question number 19 Adapted from N/A
19.
[Maximum mark: 1]
21M.1A.SL.TZ2.19

Which gases have made the most significant contributions to global warming?

A. Water and carbon dioxide

B. Carbon dioxide and methane

C. Methane and nitrous oxide

D. Carbon dioxide and ozone

[1]

Markscheme

A

Examiners report

Though most candidates opted for answer B (carbon dioxide and methane), the question discriminated well with the better students correctly giving response A (water and carbon dioxide). This should have been one of the easier questions as the required knowledge came directly from 4.4 in the guide (Climate change):

Carbon dioxide and water vapour are the most significant greenhouse gases.

Other gases including methane and nitrogen oxides have less impact.

The use of the term water rather than water vapour may have confused some candidates.

Syllabus sections