Human embroy have all the genetic instuctions, in needed the become a male of frmale. The male foetus have a master gene which acts as a biological weitch, turning other genes on and off. Loss of this gene results in female which reamin sexually immature. This master gene is located on :-

Options

A. Homologous part of X-chromosome
B. Non homologur part of X-chromosome
C. All the autosome
D. Y-chromosome

Answer

**Step-by-Step Solution:**

1. **Understanding Genetic Instructions in Embryos:**
- Human embryos carry all the genetic instructions necessary for developing into either a male or a female. This indicates that both sexes have the potential to develop from the same genetic material.

2. **Identifying the Master Gene:**
- In male fetuses, there is a specific master gene that acts as a biological switch. This gene is crucial as it regulates the expression of other genes that determine sexual development.

3. **Function of the Master Gene:**
- The master gene is responsible for the development of male characteristics. If this gene is present, it activates other genes that lead to the formation of male reproductive structures (testes). Conversely, if this gene is absent, the default pathway leads to the development of female reproductive structures (ovaries).

4. **Locating the Master Gene:**
- The master gene referred to in the question is known as the SRY gene (Sex-determining Region Y). This gene is critical for male sex determination.

5. **Chromosomal Location of the SRY Gene:**
- The SRY gene is located on the Y chromosome. The presence of the Y chromosome, specifically the SRY gene, determines whether the gonads will develop into testes (male) or ovaries (female).

6. **Conclusion:**
- Therefore, the correct answer to the question is that the master gene responsible for male sex determination is located on the Y chromosome.

**Final Answer:**
The master gene is located on the Y chromosome.

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