Question

The sex of a child is determined by which of the following?

Options

• the length of the mother’s pregnancy

• the length of time between ovulation and copulation

• the presence of an X chromosome in an ovum

• the presence of a Y chromosome in a sperm

Answer 1

the presence of a Y chromosome in a sperm

Explanation:

In humans, the ovum (egg) always carries an X chromosome, whereas the sperm carries either an X chromosome or a Y chromosome. If an X-bearing sperm fertilizes the ovum, the child will be XX (female). If a Y-bearing sperm fertilizes the ovum, the child will be XY (male). Therefore, the presence of a Y chromosome in the sperm determines the sex of the child.