Question

Considering that males can have Klinefelter (XXY) syndrome, XYY, and normal XY chromosomal combinations, and females can have Turner (XO) syndrome, poly-X (XXX, XXXX), and normal XX combinations, it is obvious that
(A) maleness results from the presence of only one X chromosome
(B) maleness results from the absence of two or more X chromosomes
(C) maleness results from the minimal presence of one Y chromosome
(D) femaleness results from the presence of two or more X chromosomes

Answer 1

Answer:

(C) maleness results from the minimal presence of one Y chromosome

Explanation:

Human males have one Y and one X chromosome as their sex chromosomes. However, the human males with Klinefelter (XXY) syndrome have two copies of X chromosome as the human males but also have one Y chromosome. Similarly, human females have two X chromosomes as sex chromosomes but the females with Turner (XO) syndrome have only one X chromosome and the females with poly-X (XXX, XXXX) have more than two X chromosomes.

This means that the  Y chromosome regulates sex in human beings. If one copy of the functional Y chromosome is present in the cells, the fetus will develop into a male. The absence of a functional Y chromosome will make the fetus develop into a female.