CAIE IGCSE Biology 17.4.13 To Use a Test Cross to Identify Questions
Practise using a homozygous recessive partner and offspring phenotypes to identify an unknown dominant genotype.
- Syllabus
- 2026–2028
- Course
- Biology 0610
Exam points
- explain that a test cross uses an individual with an unknown genotype and a homozygous recessive partner
- identify the unknown individual as heterozygous if recessive-phenotype offspring are produced
- identify the unknown individual as homozygous dominant when the test-cross offspring all show the dominant phenotype
CAIE IGCSE Biology 17.4.13 To Use a Test Cross to Identify Questions question 1
[Maximum number: 1]
In guinea pigs, the allele for black fur is dominant and the allele for white fur is recessive.
A test cross can be used to determine the genotype of a guinea pig with black fur.
What would be the expected result of the test cross if the guinea pig with black fur was homozygous?
A
50\% black, 50\% white
B
25\% black, 75\% white
C
100\% black
D
100\% white
C
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