Zoology - Principles of Inheritance and Variation Question with Solution | TestHub

Hermann Henking discovered the $X$ chromosome while studying insects in the early 1890s. The sex chromosomes in birds are opposite of that in humans. Human males are heterogametic $(XY$ ), females are homogametic $(XX)$, in birds males are homogametic (ZZ) and females are heterogametic $(\mathrm{ZW})$. The " $\mathrm{W}$ " is the sex determining chromosome just as the $Y$ in humans. A bird with a $W$ is always a female. In grasshoppers, there is no $Y$ chromosome, so a grasshopper with one $X$ chromosome (symbolized as $\mathrm{XO}$ ) is normally a male, while a grasshopper with two $X$ chromosomes $(XX)$ is normally a female.