Question

A female fruitfly heterozygous for sex-linked genes is mated with normal male fruitfly. Male specific chromosome will enter the egg cells in proportion of.

• A. $1:1$
• B. $2:1$
• C. $3:1$
• D. $7:1$

Answer 1

The correct option is A $1:1$

The female Drosophila possesses two homomorphic sex chromosomes, (XX) and the male Drosophila contains two heteromorphic sex chromosomes (XY). The differential or non-homologous region of Y-chromosome is mostly heterochromatic. The female parent produces only one type of eggs (22 + X).

The male parent produces two types of gametes (22 + Y) and (22 + X). They are produced in equal proportions. As the two types of sperms are produced in equal proportions, there are equal chances of getting a male or female fly in a particular mating.

So, the correct answer is '1:1'.