Answer :
We begin by considering what crossing two plants produces in terms of offspring genotypes. The results show that half of the offspring are heterozygous ([tex]$RI$[/tex]) and half are homozygous recessive ([tex]$II$[/tex]). This pattern is consistent with a cross between:
• A red geranium with genotype [tex]$RI$[/tex], which is heterozygous, and
• A white geranium with a homozygous recessive genotype [tex]$II$[/tex].
Here’s the step-by-step explanation:
1. The [tex]$RI$[/tex] parent is heterozygous and can produce two types of gametes: one carrying the [tex]$R$[/tex] allele and the other carrying the [tex]$I$[/tex] allele.
2. The [tex]$II$[/tex] (white) parent, being homozygous recessive, produces only one type of gamete containing the [tex]$I$[/tex] allele.
3. The Punnett square for this cross is:
[tex]$$
\begin{array}{c|cc}
& I & I \text{ (white parent)} \\
\hline
R \text{ (gamete from red parent)} & RI & RI \\
I \text{ (gamete from red parent)} & II & II \\
\end{array}
$$[/tex]
4. From the Punnett square, half of the offspring have the genotype [tex]$RI$[/tex] (showing red flowers) and the other half have the genotype [tex]$II$[/tex] (showing white flowers).
Thus, based on the observed offspring combinations, we conclude that the red geranium must be heterozygous for red flowers, with the genotype [tex]$RI$[/tex].
• A red geranium with genotype [tex]$RI$[/tex], which is heterozygous, and
• A white geranium with a homozygous recessive genotype [tex]$II$[/tex].
Here’s the step-by-step explanation:
1. The [tex]$RI$[/tex] parent is heterozygous and can produce two types of gametes: one carrying the [tex]$R$[/tex] allele and the other carrying the [tex]$I$[/tex] allele.
2. The [tex]$II$[/tex] (white) parent, being homozygous recessive, produces only one type of gamete containing the [tex]$I$[/tex] allele.
3. The Punnett square for this cross is:
[tex]$$
\begin{array}{c|cc}
& I & I \text{ (white parent)} \\
\hline
R \text{ (gamete from red parent)} & RI & RI \\
I \text{ (gamete from red parent)} & II & II \\
\end{array}
$$[/tex]
4. From the Punnett square, half of the offspring have the genotype [tex]$RI$[/tex] (showing red flowers) and the other half have the genotype [tex]$II$[/tex] (showing white flowers).
Thus, based on the observed offspring combinations, we conclude that the red geranium must be heterozygous for red flowers, with the genotype [tex]$RI$[/tex].
