What is the sex chromosome set for a typical human male?

• A. XX
• B. XY
• C. YY
• D. XZ

Answer: (B)

In humans, sex is determined by the two sex chromosomes, of which the Y chromosome is present only in males. A typical human male has one X chromosome and one Y chromosome, written as XY. The Y carries the SRY gene that directs development toward male-typical gonads and traits, while having two X chromosomes leads to female development. So the sex chromosome set for a typical human male is XY. The other patterns don’t fit because XX is seen in females, YY isn’t viable in humans, and XZ isn’t a human chromosome configuration.