Question

flower, all of the offspring are covered in both red and white petals.
a scientist crosses a red flower (rr) with a red-and-white (rw) flower.
what are the predicted phenotypes of their offspring?
choose 1 answer:
a all of the offspring will have red-and-white petals.
b 50% of the offspring will be red, and 50% of the offspring will be red-and-white
c all of the offspring will have red petals.
d 75% of the offspring will be red, and 25% of the offspring will be white.

Explanation:

To determine the phenotypes of the offspring, we use a Punnett square. The red flower has genotype \( RR \), so it can only contribute \( R \) alleles. The red - and - white flower has genotype \( RW \), so it can contribute either \( R \) or \( W \) alleles.
When we set up the Punnett square:

• The top row (from the \( RR \) parent) has \( R \) and \( R \).
• The left - hand column (from the \( RW \) parent) has \( R \) and \( W \).

The possible genotypes of the offspring are:

• When we combine \( R \) (from \( RR \)) and \( R \) (from \( RW \)), we get \( RR \) (red phenotype).
• When we combine \( R \) (from \( RR \)) and \( W \) (from \( RW \)), we get \( RW \) (red - and - white phenotype).

Since the \( RR \) parent will always give an \( R \) allele, and the \( RW \) parent gives an \( R \) allele 50% of the time and a \( W \) allele 50% of the time. So, 50% of the offspring will have the genotype \( RR \) (red phenotype) and 50% will have the genotype \( RW \) (red - and - white phenotype).

Answer:

B. 50% of the offspring will be red, and 50% of the offspring will be red - and - white