The twenty-third pair of chromosomes in humans is known as:

Male heterogamety is a characteristic of which of the following?

The sex in $Drosophila \text{ } melanogaster$ is determined by

While solving the problem of sex determination in a large number of insects,it was observed that

In which of the following organisms is male heterogamety absent?

$A$ fruit fly is heterozygous for a sex-linked gene. It is crossed with a normal female fruit fly. The specific chromosome for the male enters the egg in the ratio of ............. (in $: 1$)