Question

Drosophila flies with $XXY$ genotype are females, but human beings with such genotype are abnormal males. It shows that

• A. Y-chromosome is essential for sex determination in Drosophila
• B. Y-chromosome is female determinating in Drosophila
• C. Y-chromosome is male determining in human beings
• D. Y-chromosome has no role in sex determination either in Drosophila or in human beings

Answer 1

Answer: (C)

In human beings, the presence of a $Y$- chromosome is required for the development of a male sex phenotype. $X$-chromosomes present in any number $(XXX,XXXX)$ in the absence of a $Y$-chromosome gives rise to female. Presence of even a single $Y$-chromosome confers maleness. In Drosophila, $Y$-chromosome plays no significant role in sex determination. In Drosophila male determiners were located on autosomes. One $X$ and two autosomes produce male while two $X(X,X)$ and two autosomes produce female.