Question

Appearance of which of the following phenotypic ratio indicates polygenic inheritance?

• A. 1 : 2 : 1
• B. 12 : 3 : 1
• C. 1 : 4 : 6 : 4 : 1
• D. 27 : 9 : 9 : 9 : 3 : 3 : 3 : 1

Answer 1

Answer: (C)

Polygenic inheritance occurs when one characteristic is controlled by two or more genes. Often the genes are large in quantity but small in effect. Examples of human polygenic inheritance are height, skin colour, eye colour and weight. eg-Parental genotypes for crosses between the white and red will be - "aabbcc" for white, and "AABBcc" or "aaBBCC" or "AAbbCC" for a light-red. All first-generation offspring will be light-red wheat (for example "AaBbcc"). As a result of crossing first-generation hybrids, obtain the Traits phenotypes ratio 1:4:6:4:1