Question

the observed phenotypes and genotypes are shown in the table.
genotype/phenotype results (number)
aabb (purple, long) 729
aabb (red, round) 721
aabb (purple, round) 28
aabb (red, long) 22
notice that some offspring have the same phenotype as either parent and some have a unique combination of traits. offspring with these unique phenotypes are called “recombinant” and occur as a result of a crossing - over event between the genes for each trait. explore figure 12.19 to learn more about recombination.
what is the observed recombination frequency?
3.3 percent
5.0 percent
25 percent
1.7 percent

Explanation:

Step1: Identify recombinant genotypes

Recombinant genotypes are Aabb and aaBb.

Step2: Calculate number of recombinants

Number of Aabb = 28, number of aaBb = 22. So total recombinants = 28 + 22 = 50.

Step3: Calculate total number of offspring

Total offspring = 729+721 + 28+22 = 1500.

Step4: Calculate recombination frequency

Recombination frequency = $\frac{\text{Number of recombinants}}{\text{Total number of offspring}}\times100\%=\frac{50}{1500}\times100\%\approx 3.3\%$

Answer:

3.3 percent