Principles Of Inheritance And Variation Ques 175
175. Albinism is known to be due to an autosomal recessive mutation. The first child of a couple with normal skin pigmentation was an albino. What is the probability that their second child will also be an albino?
(a) 25%
(b) 50%
(c) 75%
(d) 100%
Show Answer
Answer : a
Hints & Solution
(a) A child will be albino only if it is homozygous for albinism genes (since albinism is a recessive character). As parents have normal skin, it means they are heterozygous. As a result of cross between two heterozygous parents, 25% of the children will be homozygous recessive. The nature of the second child is not affected in any way by the nature of the first child because both are independent events.
BETA
