Question

Sex is determined by different factors in various species. However, in human beings, it is determined genetically. Which amongst the following option(s) is/are correct for human beings ?
Gamete carrying X chromosome from female parent.
Gamete carrying X chromosome from male parent.
Gamete carrying Y chromosome from male parent.

• A. (ii) and (iii)
• B. (i) only
• C. (i) and (iii)
• D. (iii) only

Hint:

In competitive exams, remember that "determination" implies choice or variation. Since the mother's contribution is fixed (always X), the father's contribution is the "determining" factor.

Answer 1

The Correct Option is A

To determine the correct options for how sex is determined genetically in human beings, we must understand the genetic basis of sex determination in humans:

1. Genetic Basis of Sex Determination: In humans, sex is determined by the presence of two types of sex chromosomes: X and Y. Females have two X chromosomes (XX), and males have one X and one Y chromosome (XY).
2. Role of Gametes: During reproduction, females produce eggs containing only the X chromosome, while males produce sperm that can carry either an X or Y chromosome.
3. Combining Gametes: The type of sperm that fertilizes the egg determines the sex of the offspring:
   • If a sperm carrying an X chromosome fertilizes the egg, the result is a female offspring (XX).
   • If a sperm carrying a Y chromosome fertilizes the egg, the result is a male offspring (XY).
4. Correct Options Analysis:
   • Option (ii): "Gamete carrying X chromosome from male parent." This is correct because the X chromosome from the male contributes to the formation of a female child (XX).
   • Option (iii): "Gamete carrying Y chromosome from male parent." This is also correct because the Y chromosome from the male leads to the formation of a male child (XY).
5. Ruling Out Other Options:
   • Option (i): "Gamete carrying X chromosome from female parent." While this is true (females provide an X chromosome), it by itself does not determine the sex. The male gamete determines the sex by providing either an X or Y chromosome.

Thus, the correct answer is: (ii) and (iii). These options correctly indicate how genetic sex determination works in humans and emphasize the role of the male gamete in determining the sex of the offspring.