# How do you find the ratio of the offspring phenotype?

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To find a phenotypic ratio, we look at the alleles of the parent organisms and estimate how often those genes will be exhibited by the offspring.

## How do you find the ratio of offspring genotype?

To find the genotypic ratio, count the number of times each combination appears in the grid, starting in the upper left square. The example in Figure 1 below is crossing alleles for just one trait, flower color. Larger Punnett squares are used to calculate genotypic ratios for more than one trait as shown in Figure 2.

## What is the ratio for phenotypes?

This 1:1:1:1 phenotypic ratio is the classic Mendelian ratio for a test cross in which the alleles of the two genes assort independently into gametes (BbEe × bbee).

## What is the ratio of the offspring?

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.

## How do you calculate the expected phenotype ratio?

For the expected ratio (Column 4), use 9:3:3:1, the theoretical ratio for a dihybrid cross. 4. To calculate the expected number (Column 5), multiply the number of each grain type by the expected fractional ratio for that grain phenotype. The fractional ratios for these four phenotypes are 9/16, 3/16, 3/16 and 1/16.