If red (RR) is crossed with white (rr) and produces a pink flower (Rr), and tall (D) is dominant to dwarf (d), the F₂ phenotypic ratio from a cross of RR dd with rr DD would be A)9:3:3:1. B)1:1:1:1. C)1:2:2:4:1:2:1:2:1. D)3:6:3:1:2:1. E)none of these.

Question

Quizplus · Accepted Answer

The phenotype of the parent with red flowers and dwarf stature is RR dd, while the other parent with white flowers and tall stature is rr DD. Therefore, when they are crossed, their offspring will be Rr Dd, Rr DD, rr dd, and rr Dd.

The phenotype of Rr Dd is pink flowers and tall stature. The phenotype of Rr DD is pink flowers and tall stature. The phenotype of rr dd is white flowers and dwarf stature. The phenotype of rr Dd is white flowers and dwarf stature.

Therefore, the phenotypic ratio of the offspring is 3 pink and tall: 6 white and dwarf: 3 pink and dwarf: 1 white and tall: 2 pink and heterozygous for dwarf: 1 white and heterozygous for tall. This can be simplified to 3:6:3:1:2:1, which is the ratio in choice D.

If Red (RR) Is Crossed with White (Rr) and Produces