DP Biology (first assessment 2025)

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Question 19M.1A.SL.TZ1.15

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Date May 2019 Marks available [Maximum mark: 1] Reference code 19M.1A.SL.TZ1.15
Level SL Paper 1A Time zone TZ1
Command term Determine Question number 15 Adapted from N/A
15.
[Maximum mark: 1]
19M.1A.SL.TZ1.15

Creeper in chickens is a condition in which the chickens are born with very short legs. The creeper allele (C) is dominant over the normal allele (c). Embryos which are homozygous for the dominant allele fail to develop into viable chickens and die before they hatch. What phenotypic ratio would you expect in the live offspring of a cross between two creeper chickens?

A. All creeper

B. 1 creeper; 2 normal

C. 2 creeper; 1 normal

D. 3 creeper; 1 normal

[1]

Markscheme

C

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