Question

Hypertrichosis (hairy pinnae) is a trait linked to
(a)X-chromosome
(b)Y-chromosome
(c)Autosomes
(d)None of the above

Answer 1

Hint: This is one among two sex chromosomes in humans and lots of other animals. It’s normally the sex-determining chromosome in many species. The presence or absence of this chromosome typically determines the male or female sex of offspring produced in sexual reproduction. In mammals, this chromosome contains the gene SRY, which triggers male development.

Complete answer:
Hypertrichosis is excessive growth of hair on a specific area of the body which is abnormal for the age, sex, or race of an individual. The presence of the excessive coarse black hair on the auricle of the human ear is mentioned as hypertrichosis pinnae auris or hairy ears. The condition is primarily restricted to older men and infrequently observed in females. Consistent with the available literature, hypertrichosis pinnae auris is a Y-linked character. A variety of studies have shown that the inheritance of the trait is from father to son, any exceptions are often attributed to the shortage of penetrance of the gene or crossover from Y to X chromosome.

Additional Information: The research is critical for examining morphological variations and their genetic basis, sex differences among individuals and populations alongside intergroup differences requiring anthropology, anatomy, comparative morphology, personal identification, and human genetics.
So, the correct answer is 'Y-chromosome'.

Note: There's controversy over whether auricular hypertrichosis is a Y-linked or autosomal trait, or perhaps both (in different families). It has been proposed also that this phenotype results from the interaction of two loci, one on the homologous part of the X and Y and one on the non homologous sequence of the Y. Hair growth within the ear canal is usually observed to extend in older men, alongside increased growth of nose hair.