Question

Hemophilia B, a blood clotting disorder, is an X-linked recessive trait. What is the expected percentage of offspring with hemophilia that would be produced by a father who does not have hemophilia and a mother who is heterozygous for this trait

Answer 1

Answer:

The correct answer is 25%.

Explanation:

Considering that Hemophilia B is an X-linked recessive disease, than for it to be observed in female offspring, the mother must be homozygous recessive because females have XX chromosomes and if the father transfers only the dominant gene then the female offspring will always be heterozygous dominant.

In the case of a father who carries the dominant gene on his X choromosome and a mother who is heterozygous for the disease meaning she has both the dominant and the recessive gene, if we calculate the percentages for this situation, we see that for the first generation, one female offspring is heterozygous dominant, one female offspring if homozygous, one male offspring carries the dominant gene on his X chromosome and the other male offspring carries the recessive gene on his X choromosome which is the one that carries the disease.

I hope this answer helps.