Question

Haemophilic man marries a normal woman. Their offsprings will be
A. All haemophilic
B. All boys haemophilic
C. All girls haemophilic
D. All normal

Answer 1

Haemophilia is a genetic disorder in which an individual lost his ability to clot blood whenever there is a cut in the body. Which results in bleeding for longer time during injuries are sometimes, develops risk of internal bleeding in brain vessels or at joints.

Complete answer:
Haemophilia is a sex-linked disorder which is caused by mutations in the X-chromosome. Haemophilia is caused by the mutation in recessive X-chromosome.
Now, if a male individual has mutation in X chromosome, he will be suffering from the disease as another sex chromosome in male individual is Y chromosome. Thus, male will be infected by the haemophilia.

In the given condition, an infected male marries a normal female. And in the given diagram we can see that the infected male will produce two gametes having one infected X chromosome and another normal Y chromosome. Normal female will produce two normal X chromosomes.
Now, After the fertilization four possibilities will be there:
Female having one chromosome infected and another normal female thus, this female will not be infected but will be carrier of the haemophilia.
Female having one chromosome infected and another normal female. So, this female will also be a carrier and will not have haemophilia.
Male with XY pair of sex chromosome, which means will be healthy male.
And male with XY chromosome pairs will not be infected by haemophilia.

So, we can conclude that all offsprings will be normal. And option ‘D’ is the correct answer.

Note: In case of humans, male individual has sex chromosomes as XY and in female individuals, sex chromosome pair is XX. So, if a female has a mutation in her X chromosome, she will have another X chromosome working properly and she will not be infected by the disease but she can be a carrier of the disease.
Thus, female to be infected, homozygous condition should be there which means both X chromosomes of the sex chromosome pair should be mutated.