CAIE IGCSE Biology 17.4.17 Red-green Colour Blindness
Practise applying recessive X-linked inheritance to red-green colour blindness in genotypes, pedigrees and crosses.
- Syllabus
- 2026–2028
- Course
- Biology 0610
Exam points
- state that the recessive colour-blindness allele is carried on the X chromosome
- explain why one recessive X allele affects a male but a female generally needs two
- predict affected sons and daughters from parental X-linked genotypes
17.4.17—Red-green colour blindness question 1
The gene for red-green colour vision is on the X chromosome.
There are two alleles for this gene:
- The allele for normal colour vision is represented by the letter B.
- The allele for red-green colour blindness is represented by the letter b.
Fig. 5.1 shows a pedigree chart for a family in which some of the members are red-green colour-blind.
Fig. 5.1
Explain why all of the male children of parent 1 and parent 2 are red-green colour-blind.
All question bank results loaded