Question

1. in snapdragon flowers, petal color is controlled by incomplete dominance. when a plant with red flowers is crossed with a plant with white flowers, a flower with pink petals is produced. write the genotypic and phenotypic outcomes if two pink petaled snapdragons are crossed.

Explanation:

Step1: Define Genotypes

Let \( R \) represent the allele for red flowers and \( W \) represent the allele for white flowers. Since red (\( RR \)) crossed with white (\( WW \)) gives pink (\( RW \)), pink - petaled plants have genotype \( RW \).

Step2: Set Up Punnett Square

When we cross two pink - petaled plants (\( RW\times RW \)), the Punnett square is set up as follows:

	\( R \)	\( W \)
\( W \)	\( RW \)	\( WW \)

Step3: Determine Genotypic Ratios

From the Punnett square, the genotypic combinations are:

• \( RR \): 1 out of 4 (or \( \frac{1}{4} \))
• \( RW \): 2 out of 4 (or \( \frac{1}{2} \))
• \( WW \): 1 out of 4 (or \( \frac{1}{4} \))

So the genotypic ratio is \( RR:RW:WW = 1:2:1 \).

Step4: Determine Phenotypic Ratios

• Plants with genotype \( RR \) have red flowers.
• Plants with genotype \( RW \) have pink flowers.
• Plants with genotype \( WW \) have white flowers.

Since the number of \( RR \) is 1, \( RW \) is 2 and \( WW \) is 1, the phenotypic ratio is red: pink: white \( = 1:2:1 \).

Answer:

Genotypic outcome: The genotypic ratio is \( RR:RW:WW = 1:2:1 \) (i.e., 25% \( RR \), 50% \( RW \), 25% \( WW \)).
Phenotypic outcome: The phenotypic ratio is red: pink: white \( = 1:2:1 \) (i.e., 25% red - flowered, 50% pink - flowered, 25% white - flowered).