CAIE IGCSE Biology 17.4.16 Sex-linked Characteristics
Practise defining sex linkage and interpreting X-linked genotypes, carriers and unequal incidence between sexes.
- Syllabus
- 2026–2028
- Course
- Biology 0610
Exam points
- define a sex-linked characteristic as controlled by a gene on a sex chromosome
- explain that its chromosome location can make the feature more common in one sex
- use X-linked allele notation to identify affected males and carrier females
17.4.16—Sex-linked characteristic as a feature question 1
The eye is adapted for focusing on near and distant objects.
Fig. 3.1 shows the parts of the eye involved in focusing. The eye is focused on a distant object.
Fig. 3.1
Colour blindness can be caused by a mutation in a gene. The gene is located on the X chromosome.
Fig. 3.3 is a pedigree diagram of a family which has several people who are colour-blind.
Fig. 3.3
Colour blindness is sex-linked.
State the evidence from Fig. 3.3 that supports the idea that colour blindness is sex-linked.
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