Using a Punnett square, determine the genotype and phenotype ratios of the offspring from a cross between two red-yellow apple trees (Ry x Ry).

Parents: Red yellow apple $\times$ Red yellow apple
Genotypes: $Ry \times Ry$

Gametes from first parent ($Ry$): $R$, $y$
Gametes from second parent ($Ry$): $R$, $y$

Genotypes: $RR, Ry, Ry, yy$
Phenotypes:

• $RR$: Red apple
• $Ry$: Red yellow apple
• $yy$: Yellow apple

3.3.2

From the Punnett square in 3.3.1, there are 2 offspring with the genotype $Ry$ out of 4 total possible offspring.

The proportion of offspring with genotype $Ry$ is $\frac{2}{4} = \frac{1}{2}$.

The proportion of offspring with genotype $Ry$ is $\boxed{\frac{1}{2}}$.

3.3.3

• Red apple: $RR$
• Red yellow apple: $Ry$
• Yellow apple: $yy$

From the Punnett square, the genotypes are $1 RR : 2 Ry : 1 yy$.
Therefore, the phenotypic ratio is:
1 Red apple : 2 Red yellow apple : 1 Yellow apple

The phenotypic ratio of the offspring is $\boxed{\text{1 Red apple : 2 Red yellow apple : 1 Yellow apple}}$.