DP Biology (first assessment 2025)

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Question 21N.1A.SL.TZ0.19

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Date November 2021 Marks available [Maximum mark: 1] Reference code 21N.1A.SL.TZ0.19
Level SL Paper 1A Time zone TZ0
Command term Question number 19 Adapted from N/A
19.
[Maximum mark: 1]
21N.1A.SL.TZ0.19

How do greenhouse gases contribute to global warming?

A. They destroy the ozone layer, allowing radiation to reach the Earth’s surface.

B. They prevent radiation from the Earth escaping into space.

C. They trap short wavelength radiation in the atmosphere.

D. They are a product of combustion, which generates heat.

[1]

Markscheme

B

Examiners report

The discrimination index was high, but only a third of candidates answered correctly. A popular misconception was that greenhouse gases trap short-wave radiation. If that was the case, visible light from the sun would be unable to penetrate the Earth’s atmosphere.

Syllabus sections