Question

In human beings, when is the sex of an individual determined?

• A. During the initial stages of pregnancy
• B. At the time of fertilisation
• C. During the later stages of pregnancy
• D. By environmental factors

Answer 1

The correct option is B At the time of fertilisation

• The sex of the child depends on the type of sperm that fertilises the egg. An egg contains only a single X chromosome, while a sperm may have either an X or a Y chromosome.
• It is a matter of chance as to which type of sperm fertilises the ovum. If the egg (X chromosome) is fertilised by an X-bearing sperm, the resulting combination is XX, i.e., female. If the egg ( X chromosome) is fertilised by a Y-bearing sperm, the resulting combination is XY, i.e., male.