IB Biology Sex Linkage

Red-green colour-blindness is a recessive, X-linked trait caused by a single gene. In marriages between a man who is colour-blind, and a woman who is a carrier, what percentage of all their children would be expected to be daughters who do not carry the trait at all?

• 50%

• 75%

• 0%

• 100%

Red-green colour-blindness is a recessive, X-linked trait caused by a single gene. In marriages between men who are colour-blind, and women who are carriers, what percentage of the sons born to these couples will not be red green colour blind?

• 50%

• 75%

• 0%

• 100%

In all conditions in which a defective gene is on the X chromosome, transmission of an allele of the condition to a male child can be:

• from neither his mother nor father

• only from his father

• only from his mother

• either from his father or his mother

Red-green colour-blindness is a recessive, X-linked trait. In marriages between a man who has normal colour vision and a woman who is a carrier of red-green colour blindness, what percentage of all the children can be expected to be sons who are colour blind?

• 25%

• 75%

• 0%

• 50%

Red-green colour-blindness is a recessive, X-linked trait. In marriages between a man who has normal colour vision, and a woman who is a carrier, what percentage of the female children can be expected to be daughters who have normal colour vision?

• 0%

• 50%

• 25%

• 100%

The pedigree diagram below shows inheritance within one family group. It shows that the trait in question is:

• sex-linked dominant

• autosomal recessive

• sex linked recessive

• autosomal dominant

The image below is a partial pedigree for the inheritance of hemophilia in the royal families

of Europe. Based upon this pedigree, the allele for hemophilia is most likely to be:

• sex-linked & recessive

• autosomal & recessive

• autosomal & dominant

• sex-linked & dominant

Which is the best explanation that Prince Sigmund of Prussia did not inherit hemophilia?

• he only inherited one hemoophilia allele from his mother

• he only inherited one hemophilia from his father

• he didn’t inherit any hemophilia alleles

• he inherited two hemophilia alleles

Colour-blindness is a recessive, X-linked trait. In marriages between a man who is colour-blind, and a woman who is a carrier, what percentage of the children can be expected to be daughters who are colour-blind?

• 100%

• 50%

• 25%

• 0%

Colour-blindness is a sex-linked trait that is uncommon in women because

• women have a different gene for colour vision

• the colour-blindness allele is carried by a gene on the Y chromosome

• women have to receive the trait from both parents in order for it to be expressed

• in women the normal allele is dominant to the colour-blindness allele