Question

Pattern baldness, moustaches and beards in human males are examples of
A)Sex-linked traits
B)Sex differentiating traits
C)Sex limited traits
D)Sex determining traits

Answer 1

Hint: Pattern baldness, moustaches and beards are the distinct features of the males. These are governed by the androgens. Development of facial hairs in males starts at the onset of puberty. Pattern baldness is the permanent loss of top hair in males. This is entirely governed by genes.

Complete answer:
To solve this question, we must discuss about the traits linked with sex.

A.Sex-linked traits- It is a trait in which is expressed due to a gene on a sex chromosome which is X or Y. In humans, it means the traits which are influenced by the X chromosome genes. The diseases like sickle cell anaemia are the example of sex-linked traits.

B.Sex differentiating traits- These are the traits which differentiate between the male and females’ development. It considers the presence of sex chromosomes. For example XX in females and XY in males.

C.Sex limited traits- These traits are present in both the sexes of sexually reproducing organisms but is only expressed in one sex and is not at all expressed in the other sex. Due to these genes, the opposite sexes show different phenotypes despite of the same genotype. Example pattern baldness, moustaches and beards.

D.Sex determining traits-These are governed by the genes which control the development of primary and secondary sexual characters.

Hence, the correct answer is option (B)

Note: Sex-limited genes were first described by Charles Darwin. These genes are responsible for sexual dimorphism. These genes show a dominant-recessive relationship in which the gene which is expressed is called dominant and the other is called recessive.