question_answer

In an organism, pink spot is a sex-linked recessive trait and black hair is dominant to white. If a pink spotted black heterozygous female is mated to a white male which is not spotted, the phenotypic ratio of the offspring would be [JIPMER 1994]

A) 1/4 spotted black; 1/4 pink spotted white; 1/4 unspotted black; 1/4 unspotted white

B) 1/2 pink spotted black; 1/2 pink spotted white

C) 3/4 pink spotted black; 1/4 pink spotted white

D) 3/4 unspotted black ; 1/4 pink spotted white

Correct Answer: A

Solution :

\[\frac{1}{4}\] Black unspotted, \[\frac{1}{4}\] Black pink spotted \[\frac{1}{4}\] White unspotted, \[\frac{1}{4}\] White, pink spotted Here B is dominant over b and R is dominant over r.