Question

Dihybrid Practice Problems

1. A cross between a plant with red flowers (R) and a plant with white flowers (r) yielded 37
plants with red flowers and 41 plans with white flowers.
a. What are the genotypes of the parent plants?
b. Explain how you got the answer to question la.

Answer 1

a. Genotype of the parents are; Rr and rr

b. Please find the explanation to A below

Step-by-step explanation:

This question involves a single gene that codes for flower color in a plant. The allele for red flower (R) is dominant over the allele for white flower (r). This means that a plant that is heterozygous for flower color (Rr) will be red.

In a cross between a plant with red flowers and white flowers, the phenotype of the offsprings is represented as: 37 plants with red flowers and 41 plants with white flowers. Observing from this number, one would realize that the phenotype ratio is equivalent to 1:1. This phenotypic ratio is only possible when the parent with red flower is heterozygous for the gene i.e. Rr. Hence, the genotype of the parents are: Rr and rr.

b) If one were to cross Rr (red flower) × rr (white flower), the phenotypic ratio of red to white offsprings will be 1:1. Hence, judging from the ratio got from the cross of the two parents above (1:1), the parental genotypes are Rr and rr.