Question

Excessive growth of hair on the pinna is a feature food only in males becuase

• A. The female sex hormone oestrogen suppresses the character in females
• B. The gene responsible for the character is present on the Y-chromosomes only
• C. The gene responsible for the character is recessive in females and dominant only in males
• D. The character is induced in males as males produced testosterone

Answer 1

Answer: (B)

The gene responsible for the character is present on the Y-chromosomes only

Genes in the non-homologous region of Y-chromosome pass directly from male to male. Y-linked genes are also called as holandric genes, In man, the Y-linked genes such as ichthyosis hystrix (spiny scales on skin), hypertrichosis (excessive development of hairs on pinna) are transmitted directly from father to son.

Thus, the correct answer is option B.