Question

A horticulturalist wants to produce geraniums with specific characteristics. She knows that the trait of red flowers is governed by the allele R (RR and Rr) and the trait of white flowers is governed by the allele r (rr).
The horticulturalist has a red geranium with an uncertain genetic makeup. She crosses it with a white geranium (rr) 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 makep of the red geranium parent?

a. The red geranium is heterozygous for red flowers (Rr).
b. The red geranium is homozygous for red flowers (RR).
c. The trait shows incomplete dominance.
d. The red geranium is homozygous for white flowers (rr).

I'm not sure about this question.

Answer 1

The answer is  A -The red geranium is heterozygous for red flowers (Rr).

We know that the red flower, to be red needs to have at least a dominant allele, so it could be either Rr or RR.
Let's try both scenarios.
If the white geranium (rr) is being crossed with RR, all the offspring would be red with genotype: Rr.
On the other hand, if the flower is Rr and it's being crossed with rr, that would result in half of the new generation plants having red flowers and the other half white flowers.