Question

In F${}_2$ generation, quantitative inheritance ratio 1 : 4 : 6 : 4 : 1, is obtained instead of

• A. 9 : 3 : 3 : 1
• B. 8 : 6 : 4 : 1
• C. 7 : 4 : 1 : 4
• D. 6 : 6 : 4 : 7

Answer 1

The correct option is A 9 : 3 : 3 : 1

A cross between two genotypes, that are heterozygous for two genes, is called as dihybrid cross. A cross between two dihybrids gives 9 : 3 : 3 : 1 phenotypic ratio. When the trait is controlled by one or more genes, the dominant alleles of which show a cumulative effect, i.e., only part of the trait is expressed by single dominant allele and expression of a full trait requires the presence of all dominant allele, it is quantitative inheritance. The phenotype of offspring depends on a number of dominant alleles. The dihybrid cross ratio for quantitative inheritance is 1 : 4 : 6 : 4 : 1. Option A is correct.