Here's why:

* Chromosomes: Humans have 23 pairs of chromosomes, totaling 46 chromosomes.

* Pairs: Most chromosomes exist in pairs, one from each parent.

* Sex Chromosomes: The 23rd pair are the sex chromosomes. They determine your biological sex.

* Females: XX - Two X chromosomes

* Males: XY - One X and one Y chromosome

Therefore, in a male cell, only one Y chromosome is present.