A horticulturalist wants to produce geraniums with specific characteristics. She knows that the trait of red flowers is governed by the allele [tex]R (RR[/tex] and [tex]Rr)[/tex] and the trait of white flowers is governed by the allele [tex]r (rr)[/tex].

The horticulturalist crosses two geraniums from the F1 generation. Look at the Punnett square to see this cross.

[tex]\[

\begin{tabular}{|c|c|c|}

\hline

& R & r \\

\hline

R & RR & Rr \\

\hline

r & Rr & rr \\

\hline

\end{tabular}

\][/tex]

Which ratio of red-to-white flowering plants would she expect to see in the phenotypes of the F2 generation?

A. 3 red : 1 white
B. 1 red : 3 white
C. 2 red : 2 white
D. All red

To understand the ratio of red to white flowering plants in the F2 generation, we need to interpret the given Punnett square.

The Punnett square for the cross shows the following possible genotypes for the offspring:

1. [tex]$ RR $[/tex]
2. [tex]$ Rr $[/tex]
3. [tex]$ Rr $[/tex]
4. [tex]$ rr $[/tex]

Now, let's determine the phenotype for each genotype:

- Red flowers: The genotypes [tex]$ RR $[/tex] and [tex]$ Rr $[/tex] will result in red flowers because the allele for red flowers, [tex]$ R $[/tex], is dominant.
- White flowers: The genotype [tex]$ rr $[/tex] will result in white flowers because both alleles are recessive.

Looking at the possibilities:

- There is one [tex]$ RR $[/tex], which results in red flowers.
- There are two [tex]$ Rr $[/tex], which also result in red flowers.
- There is one [tex]$ rr $[/tex], which results in white flowers.

So, we count the number of red and white flowering plants:

- Red flowering plants: [tex]$ RR, Rr, Rr $[/tex] (1 + 2 = 3)
- White flowering plants: [tex]$ rr $[/tex] (1)

The phenotypic ratio of red to white flowering plants in the F2 generation is 3 red to 1 white.

Therefore, the expected ratio of red-to-white flowering plants in the phenotypes of the F2 generation is 3 red : 1 white.