A horticulturalist wants to produce geraniums with specific characteristics. She knows that the trait of red flowers is governed by the allele [tex]R[/tex] (either [tex]RR[/tex] or [tex]Rr[/tex]) and the trait of white flowers is governed by the allele [tex]r[/tex] ([tex]rr[/tex]). The horticulturalist has a red geranium with an uncertain genetic makeup. She crosses it with a white geranium ([tex]rr[/tex]) and gets a generation in which half of the plants have red flowers and half have white flowers.

What does this combination of offspring tell her about the genetic makeup of the red geranium parent?

Red geranium: R

White geranium: r

Then if: F1: 2/4: Red and 2/4:White

P:Rr x rr

F1: Rr, Rr, rr, rr

That means that the red geranium he crossed was heterozygous for the gene red flowers

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EvaSharma1 EvaSharma1 · Answer 2 · 2025-05-30T08:48:04-04:00

The cross resulting in half red and half white flowers indicates that the red geranium parent was heterozygous (Rr), displaying incomplete dominance.

The combination of offspring colors observed when the red geranium with an uncertain genetic makeup is crossed with a white geranium (rr) and results in half red and half white flowers indicates that the red geranium parent is heterozygous for the flower color gene. This is because the phenotypic ratio of 1:1 is characteristic of a cross between a heterozygote (Rr) and a homozygous recessive (rr). This is an example of incomplete dominance, where the R allele (red flower color) is not completely dominant over the r allele (white flower color), thus producing pink flowers in the heterozygote (Rr).