Write the amount of homozygous dominant (AA) and heterozygous (Aa) squares as one phenotypic group.
Count the amount of homozygous recessive (aa) squares as another group.
Write the result as a ratio of the two groups.
A count of 3 from one group and 1 from the other would give a ratio of 3:1.
What is a phenotypic ratio?
Phenotypic ratio pertains to the relative number of offspring manifesting a particular trait or combination of traits. It can be determined by doing a test cross and identifying the frequency of a trait or trait combinations that will be expressed based on the genotypes of the offspring.
How do you find the genotype and phenotypic ratio?
Genotypic Ratios and Phenotypic Ratios for Punnett Squares
What is the genotype ratio?
The genotypic ratio describes the number of times a genotype would appear in the offspring after a test cross. For example, a test cross between two organisms with same genotype, Rr, for a heterozygous dominant trait will result in offspring with genotypes: RR, Rr, and rr.