Final answer:
The pair of sex chromosomes passed from a parent to a child that determines the child's biological sex is the XX or XY pair. Females have two X chromosomes (XX. The sex of the baby is determined by the father.
Step-by-step explanation:
The pair of sex chromosomes passed from a parent to a child that determines the child's biological sex is the XX or XY pair. Females have two X chromosomes (XX), while males have one X chromosome and one Y chromosome (XY).
For example: If a baby inherits an X chromosome from the father and an X chromosome from the mother, the baby will have two X chromosomes and be female. If the father's sperm carries the Y chromosome, the child will be male.
Fun fact: The mother can only pass on an X chromosome, so the sex of the baby is determined by the father.