Hypertrichosis of pinna occurs only in males because

Options

A. Esterogen suppresses the trait in females
B. It is induced by testosterone in males
C. Gene for it is present only on y-chromosome
D. Its gene is recessive in females and dominant in males.

Answer

**Step-by-Step Solution:**

1. **Understanding Hypertrichosis of Pinna**:
- Hypertrichosis of the pinna, also known as auricular hypertrichosis, is a genetic condition characterized by excessive hair growth on the outer ear (pinna).

2. **Genetic Basis**:
- The condition is linked to genetic factors. It is important to note that certain traits can be sex-linked, meaning they are associated with the sex chromosomes.

3. **Sex Chromosomes**:
- In humans, males have one X and one Y chromosome (XY), while females have two X chromosomes (XX). This difference in sex chromosomes can influence the expression of certain traits.

4. **Expression in Males vs. Females**:
- In the case of hypertrichosis of the pinna, the gene responsible for this trait is located on the Y chromosome. Since females do not possess a Y chromosome, they cannot express this trait.

5. **Conclusion**:
- Therefore, hypertrichosis of the pinna occurs only in males because the gene for it is present only on the Y chromosome.

**Final Answer**: Hypertrichosis of pinna occurs only in males because the gene for it is present only on Y chromosomes.

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