Biology · Variation and Genetics

In the given scenario where a mother is a carrier of the sex-linked recessive disease hemophilia and mates with a healthy man, the following statement is true: 50% of sons will have hemophilia. Hemophilia is an X-linked recessive disorder, which means the gene responsible for hemophilia is located on the X chromosome. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). When a carrier mother (X^hX) mates with a healthy man (XY), the possible outcomes for their offspring are as follows: Sons: There is a 50% chance that a son will inherit the X chromosome with the hemophilia allele (X^h) from the carrier mother, resulting in the son having hemophilia (X^hY). There is also a 50% chance that a son will inherit the healthy X chromosome from the mother (X) and the Y chromosome from the father (Y), resulting in the son being unaffected by hemophilia (XY). Daughters: There is a 50% chance that a daughter will inherit the X chromosome with the hemophilia allele (X^h) from the carrier mother and a healthy X chromosome from the father (X^hX). Therefore, the correct statement is that 50% of sons will have hemophilia.

This option is incorrect. * The daughters are just as likely to be hemophilic as the sons are: Daughters inherit one X chromosome from each parent. They would only have hemophilia if they inherited the affected X chromosome from both parents (xx). Since the father is healthy, this is not possible.

This option is incorrect. 50% of the daughters will have hemophilia: As explained above, daughters need to inherit the affected X chromosome from both parents to have hemophilia.

This option is incorrect. None of the children will have hemophilia because the mother is the only carrier: The mother being a carrier means she can pass the affected gene to her children, specifically her sons.

In the given scenario where a mother is a carrier of the sex-linked recessive disease hemophilia and mates with a healthy man, the following statement is true: 50% of sons will have hemophilia. Hemophilia is an X-linked recessive disorder, which means the gene responsible for hemophilia is located on the X chromosome. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). When a carrier mother (X^hX) mates with a healthy man (XY), the possible outcomes for their offspring are as follows: Sons: There is a 50% chance that a son will inherit the X chromosome with the hemophilia allele (X^h) from the carrier mother, resulting in the son having hemophilia (X^hY). There is also a 50% chance that a son will inherit the healthy X chromosome from the mother (X) and the Y chromosome from the father (Y), resulting in the son being unaffected by hemophilia (XY). Daughters: There is a 50% chance that a daughter will inherit the X chromosome with the hemophilia allele (X^h) from the carrier mother and a healthy X chromosome from the father (X^hX). Therefore, the correct statement is that 50% of sons will have hemophilia.