Question

Assertion :Haemophilia is a genetic disorder generally found in males. Reason: Haemophilia is sex-linked trait and the gene for haemphilia is located on the Y chromosome.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
• C. Assertion is correct but Reason is incorrect.
• D. Both Assertion and Reason are incorrect.

Answer 1

The correct option is C Assertion is correct but Reason is incorrect.

Haemophilia is a genetic disorder because the governing genes are present of X-chromosome which is a sex chromosome in human. The trait is transmitted to offspring in a sex-linked manner. Hence, the assertion is correct. It is an X-linked disorder since the governing genes are present on the X-chromosome and are transmitted in a sex-linked recessive manner. Since human males are hemizygous for the X-chromosome (XY), the presence of one affected allele is sufficient to express the disease in them. The females being homozygous need two copies of the recessive affected allele to show the disease; therefore it is more common in males. The governing genes are present on X-chromosomes, not on the Y-chromosomes, the reason is wrong. So, the correct answer is option C.