DP Biology (first assessment 2025)

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Question 20N.1A.SL.TZ0.35

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Date November 2020 Marks available [Maximum mark: 1] Reference code 20N.1A.SL.TZ0.35
Level SL Paper 1A Time zone TZ0
Command term Question number 35 Adapted from N/A
35.
[Maximum mark: 1]
20N.1A.SL.TZ0.35

Andalusian fowl have varied colours and types of feathers. The allele for black feathers is codominant with the allele for white, producing blue feathers in the heterozygote. The texture of feathers is controlled by another gene, with silky feathers recessive to normal. Blue silky birds are crossed with black silky birds. What is the expected proportion of blue silky offspring?

A. 0%

B. 25%

C. 50%

D. 100%

[1]

Markscheme

C

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