Final answer:
The chromosome pair present in a male child's zygote is XY. In contrast, females have XX chromosomes. The genotype XXY is indicative of Klinefelter syndrome, a genetic condition in males due to an extra X chromosome.
Step-by-step explanation:
If we look to determine the sex of a male child based on the chromosome pair present in a zygote, we find that a male zygote will have an XY chromosome configuration. This is because, in humans and other mammals, the sex of the offspring is determined by the sex chromosomes. Females typically have an XX chromosome pair, while males have an XY pair. The presence of the Y chromosome is what generally leads to male characteristics.
Regarding genetic conditions related to the number of sex chromosomes, genotype XXY corresponds to Klinefelter syndrome. This condition occurs due to nondisjunction during meiosis, which leads to a male having an extra X chromosome. Klinefelter syndrome is characterized by a set of symptoms and physical traits that are caused by the additional genetic material from the extra X chromosome.
In the case of birds, the sex determination system is different. Females have the sex chromosomes ZW, and males have ZZ, which is the opposite of how the XX and XY systems work in mammals.