Question

In complementary gene interaction genotypic ratio is

• A. 9 : 7
• B. 9 : 3 : 3 1
• C. 12 : 3 : 1
• D. 1 : 2 : 2 : 4 : 1 : 2 : 1 : 2 : 1

Answer 1

The correct option is A 9 : 7

Complementary genes are two pairs of non allelic dominant genes that interact to produce only one phenotypic trait but neither of them when present alone, produces the trait in absence of the other allele. Hence for the development of dominant character, presence of both the genes is necessary. For example, the flower colour in Lathyrus odoratus is dependent upon two non allelic complementary genes C and P as shown in the figure.

Hence, in a complementary gene interaction, genotypic ratio is 9:7.

So, the correct answer is '9:7'.