Question

It is a commonly held misconception that the mother's egg is responsible for determining whether the baby will be a boy or a girl. But actually, it is the father's sperm, which decides this.

Which of the following makes the sperm the decisive factor?

• A. More number of male gametes fuse with the female gamete during fertilization.
• B. There are more number chromosomes in male gametes compared to female gametes.
• C. Hormones are secreted only in the males which determine the sex of the baby.
• D. A male gamete can have either of the two sex chromosomes (X or Y), while the female gamete has only one (X).

Answer 1

Answer: (D)

A male gamete can have either of the two sex chromosomes (X or Y), while the female gamete has only one (X).

Sperm can have either of the two sex chromosomes, while the egg has only one sex chromosome. Sex in humans is determined genetically by the presence of a combination of a pair of sex chromosomes. In humans, 22 chromosome pairs are autosomes and the 23rd pair is the sex chromosome. In females, the sex chromosomes are XX and in males, it is XY. Thus, the gamete produced by females contains X while in males, 50% of gametes contain the X chromosome and 50% contain the Y chromosome. If the sperm containing the X chromosome fertilizes the egg, the child born is a female and if the sperm containing the Y chromosome fertilizes the egg, the child born is a male.

Thus, the correct answer is option D.