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2.2 Sex Linkage — Colour Blindness & Haemophilia — Test 1
Q1. Genes for colour blindness in man are located on the:✓ X chromosome only
Q2. Red-green colour blindness is caused by:✓ A recessive gene on the X chromosome
Q3. Red-green colour blindness is an example of which type of genetic disorder?✓ X-linked recessive
Q4. X-linked red-green colour blindness affects about 1 in 12 (≈8%) of Swiss males. The expected proportion of colour-blind Swiss females is approximately:✓ 0.7%
Q5. Colour blindness is X-linked recessive. From a normal father and a carrier mother, the probability that a child is colour blind is:✓ 1/4
Q6. The children of a colour-blind mother and a normal father will be:✓ Colour-blind sons and carrier daughters
Q7. A woman has a colour-blind father but a husband with normal vision. The chances of colour-blind sons and daughters are:✓ 1/2 sons, zero daughters
Q8. A colour-blind man has a normal brother and a colour-blind sister. Regarding the parents, it is most likely that:✓ Father colour-blind and mother a carrier
Q9. A colour-blind female is rare because she will be born only when:✓ Her father and maternal grandfather are colour blind
Q10. A female is heterozygous (carrier) for colour blindness. Which relative could NOT have contributed the colour-blindness allele to her?✓ Paternal grandfather
Q11. Haemophilia, a blood-clotting disorder, is due to a:✓ Recessive X-linked mutation
Q12. Haemophilia is more common in males because it is:✓ Recessive X-linked
Q13. Haemophilia-A results from a deficiency of:✓ Clotting factor VIII
Q14. Hemophilia and colour blindness are both:✓ X-linked recessive
Q15. Both father and son are haemophilic and the mother is phenotypically normal. The genotype of the mother is:✓ X^H X^h
Q16. A man with hemophilia has a phenotypically normal daughter who marries a normal man. The probability that their daughter is a hemophiliac is:✓ 0%
Q17. Which of the following is an X-linked recessive disorder?✓ Haemophilia
Q18. The sex of a human baby is determined by the:✓ Sperm
Q19. The number of sex chromosomes present in a normal human sperm is:✓ 1
Q20. Match each X-linked situation with its outcome and select the correct option.✓ A-iii, B-iv, C-i, D-ii