Which statement about inheritance is true?
A. Girls get most of their traits from their moms; boys get most of their traits from their dads.
B. Male offspring will always have an X-linked genetic disease if the mom is a carrier.
C. Fathers always determine the gender of the offspring in humans.
D. Males never have Y chromosomes.
The Correct Answer and Explanation is :
The correct answer is C. Fathers always determine the gender of the offspring in humans.
Explanation
In humans, sex determination is primarily based on the presence of sex chromosomes. Each individual typically has 23 pairs of chromosomes, where one pair consists of the sex chromosomes—XX for females and XY for males. The father contributes one of his two sex chromosomes (either X or Y) to the offspring, while the mother always contributes one of her X chromosomes. Therefore, the combination of these chromosomes determines the biological sex of the child:
- If the father contributes an X chromosome, the child will be female (XX).
- If the father contributes a Y chromosome, the child will be male (XY).
This means that the father’s sex chromosome is crucial in determining the gender of the offspring, which is why statement C is true.
Why Other Statements Are Incorrect
- A. Girls get most of their traits from their moms; boys get most of their traits from their dads. This statement is misleading because both males and females inherit traits from both parents. While certain traits might be influenced more strongly by one parent due to maternal or paternal genetic contributions, there is no blanket rule regarding the distribution of traits based on gender.
- B. Male offspring will always have an X-linked genetic disease if the mom is a carrier. This statement is incorrect because male offspring will only inherit an X-linked genetic disease if they receive the affected X chromosome from their mother. If the mother is a carrier, there’s a 50% chance that a son will inherit the affected X, and a 50% chance he will inherit the unaffected X.
- D. Males never have Y chromosomes. This statement is false. Males have one Y chromosome and one X chromosome (XY), while females have two X chromosomes (XX). Thus, all typical males possess a Y chromosome.
Understanding these basics of genetics helps clarify the inheritance patterns and roles of sex chromosomes in determining biological sex.