Dihybrid cross refers to a cross between the two distinct groups, which vary in two observed traits. For the genes on different chromosomes, each of the allelic pair demonstrated independent segregation.
If the initial filial generation generates four similar offspring, the latter filial generation, which takes place by crossing the members of the initial filial generation, demonstrates phenotypic ratio of 9:3:3:1.
Therefore, dividing the 80 progeny on the basis of the ratio 9:3:3:1, one can anticipate five snails to be homozygous recessive for both the traits. The calculation is to be done on the basis of the ratios and proportions, that is, the sum of ratio numbers 9+3+3+1 = 16.
80*1/16 = 5