Female humans have which sex chromosome pair?

In humans, each cell normally contains 23 pairs of chromosomes, for a total of 46. The first 22 pairs, called autosomes, look the same in both males and females. The 23rd pair, the sex chromosomes, differ between males and females: 1. **Females** have two $X$ chromosomes in their cells, denoted as $XX$. 2. **Males** have one $X$ and one $Y$ chromosome, denoted as $XY$. Because biological females receive an $X$ chromosome from both the mother (egg) and the father (sperm), the resulting pair is $XX$.