Question

Given below is the pedigree chart of the inheritance of haemophilia. Answer the following questions with the help of this chart-

(a) From both parents who is the carrier of this disease?
(b) What will be the genotype of child 1 and 2?
(c) Explain the genotype of child 3 with a cross.
(d) Name one other trait in humans which follows the same pattern of inheritance.

Answer 1

Hemophilia is a sex-linked recessive disorder of humans. The pedigree chart given below shows the inheritance of Hemophilia in one family.

Study the pattern of inheritance and answer the questions given.

1. Give all the possible genotypes of the members 4, 5, and 6 in the pedigree chart.

2. A blood test shows that individual 14 is a carrier of hemophilia. The member numbered 15 has recently married the member number 14. What is the probability that their first child will be a hemophilic male?

(CBSE 2009, CBSE Sample Paper 2018-19)

Answer:

Genotypes of member 4 – XX or XXh Genotypes of member 5 – XY Genotypes of member 6 – XY

The probability of the first child being a hemophilic male is 50%