Question

Which of the following pair of features is a good example of polygenic inheritance?

• A. Hair pigment of mouse and tongue rolling in humans
• B. Human height and skin colour
• C. Human eye colour and sickle cell anaemia
• D. ABO blood group in humans and flower colour of Mirabilis jalapa

Answer 1

The correct option is B Human height and skin colour

A polygenic trait is the one that is governed by more than one gene. Human skin colour is a polygenic trait governed by more than one gene where dominant allele of each gene express only a part of trait and the full trait is expressed only in the presence of dominant alleles of all multiple genes, is called as polygenic inheritance. These genes control skin pigmentation only, no other phenotypic trait is affected by these genes. Likewise, human eye colour and hair pigment in the mouse are polygenic but tongue rolling in humans is not polygenic which makes option A incorrect. Human blood group inheritance is the example of codominance and multiple alleles. It is governed by three alleles namely $I^A$, $I^B$ and i. Flower colour in Mirabilis jalapa is governed by two alleles of a gene that show incomplete dominance; option D is incorrect. Sickle cell anaemia is governed by two alleles of a gene $H{b}^b$ and $H{b}^s$ which makes option C incorrect. The correct option is B.