Question

Which one of the following is the sex-linked character in human inheritance?
A. Diabetes insipidus
B. Color-blindness
C. Breast in females
D. Beard in males

Answer 1

Sex-linked characters are the traits that are linked with a particular chromosome which also determines the sex. Diabetes insipidus is a hormonal imbalance disease. In colorblindness, the eye cannot distinguish between the red and the green colors. Moreover, the growth of certain body parts like breasts and beard are related to the genome.

Complete answer: Let us look at all the options that are given to us one by one.
-Diabetes insipidus: Diabetes insipidus is a condition in which the salt and the water metabolism of the body is imbalanced. This disease is characterized by extreme thirst and frequent urination. This is because the body cannot regulate the fluids. Diabetes mellitus is caused due to the hormonal disbalance of the hormones of the hypothalamus and pituitary gland.
-Color-blindness: Color-blindness is the recessive sex-linked trait of the X-chromosome. The genes for normal vision are dominant. The X-chromosome carries the normal gene and the recessive allele for it. In females, when both the sex chromosomes carry the recessive gene, then only the person is colorblind. If one gene is normal and one gene is recessive in females then they have normal vision but they are carriers. In males when there is one recessive gene, then the person is colorblind because the Y-chromosome does not carry the gene for color-blindness.
-Breast in females: The breast in females is a sex-limited trait. This means that the genes for this are autosomal and are found in both the sexes, however, they express themself in one sex only. Due to this reason, the milk glands or breasts are found in females only, and in the case of males, they are underdeveloped and rudimentary.
-Beard in males: The beard in males is a sex-limited trait. This means that the genes for this are autosomal and are found in both the sexes, however, they express themself in one sex only. Due to this reason, the milk beard is found in males only, and in the case of females, it is absent.
Hence, the correct answer is option (B).

Note: Color-blindness follows a criss-cross inheritance. This means that the male transmits his traits to his grandson through his daughter while the female transmits her traits or her genes to her granddaughter through her son. Therefore, it is the transfer of the trait from one sex of the offspring to the same-sex via the opposite sex.