Answer :
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
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
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).