DP Biology (first assessment 2025)

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Question 22N.1A.SL.TZ0.20

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Date November 2022 Marks available [Maximum mark: 1] Reference code 22N.1A.SL.TZ0.20
Level SL Paper 1A Time zone TZ0
Command term Question number 20 Adapted from N/A
20.
[Maximum mark: 1]
22N.1A.SL.TZ0.20

By the end of the 19th century in England, the dark form of the moth Biston betularia formed up to 98 % of the total population in industrial areas. From 1970, the percentage of dark forms decreased significantly. What is an explanation for the decrease?

A.  An increase in environmental pollution killed the dark forms more than the light forms.

B.  Reduction of pollution resulted in greater camouflage for light forms of the moth.

C.  Dark forms could no longer find mates.

D.  Light forms had superior feeding mechanisms.

[1]

Markscheme

B

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