Answer: Part A: All female offspring of the couple will be carriers of the hemophilia gene (Xh) but will not exhibit symptoms because they have a healthy X chromosome to compensate. All male offspring will inherit the affected X chromosome from their mother, and because they only have one X chromosome, they will exhibit hemophilia. Therefore, the probability of any male offspring being affected by hemophilia is 100%, while the probability of any female offspring being carriers of the gene is 100%.
Part B: If a female child is affected by hemophilia (XhXh), it means that she inherited the affected X chromosome from both of her parents. Her mother must be a carrier of the gene (XhX) but does not exhibit symptoms of hemophilia because she has a healthy X chromosome to compensate. Therefore, the only way the female child could have inherited the affected X chromosome from both parents is if her father also had hemophilia and passed on his affected X chromosome to her.
Based on this reasoning, it is highly likely (if not certain) that the female child's father was also affected by hemophilia.
Part C: X-linked disorders usually occur more often in males of a population than in females of the population because of the difference in sex chromosomes between males and females. Males have one X and one Y chromosome, while females have two X chromosomes.
If a male inherits an X chromosome with a disease-causing gene (such as in hemophilia), he will not have a healthy version of the gene on his Y chromosome to compensate for the defect. On the other hand, females have two X chromosomes, so if they inherit one copy of the disease-causing gene, they still have a healthy copy on their other X chromosome to compensate for the defective one. In other words, females are less likely to be affected by X-linked disorders because they have a backup copy of the gene on their second X chromosome.