Answer :
To determine the expected ratio of red-to-white flowering plants in the F2 generation, we'll use the Punnett square and analyze the genetic combinations.
1. Understand the Alleles:
- The allele for red flowers is represented by [tex]\( R \)[/tex], and plants with [tex]\( RR \)[/tex] or [tex]\( Rr \)[/tex] genotypes will have red flowers.
- The allele for white flowers is represented by [tex]\( r \)[/tex], and only plants with the [tex]\( rr \)[/tex] genotype will have white flowers.
2. Set Up the Punnett Square:
- The parents from the F1 generation have genotypes [tex]\( Rr \)[/tex] and [tex]\( Rr \)[/tex], which we cross in a Punnett square.
3. Fill Out the Punnett Square:
- Each parent can pass on one allele to the offspring. We consider all combinations of these alleles:
- The possible offspring combinations are: [tex]\( RR \)[/tex], [tex]\( Rr \)[/tex], [tex]\( Rr \)[/tex], and [tex]\( rr \)[/tex].
4. Phenotype Analysis:
- Red Flowers: The genotypes [tex]\( RR \)[/tex], [tex]\( Rr \)[/tex], and [tex]\( Rr \)[/tex] produce red flowers. So, three out of the four possible combinations result in red-flowering plants.
- White Flowers: The genotype [tex]\( rr \)[/tex] results in white flowers. There is one such combination.
5. Calculate the Ratio:
- Count the number of each phenotype:
- Red-flowering plants: 3 combinations (RR, Rr, Rr)
- White-flowering plants: 1 combination (rr)
- The ratio of red-to-white flowering plants is 3:1.
Therefore, the horticulturalist can expect to see a 3:1 ratio of red-to-white flowering plants in the phenotypes of the F2 generation.
1. Understand the Alleles:
- The allele for red flowers is represented by [tex]\( R \)[/tex], and plants with [tex]\( RR \)[/tex] or [tex]\( Rr \)[/tex] genotypes will have red flowers.
- The allele for white flowers is represented by [tex]\( r \)[/tex], and only plants with the [tex]\( rr \)[/tex] genotype will have white flowers.
2. Set Up the Punnett Square:
- The parents from the F1 generation have genotypes [tex]\( Rr \)[/tex] and [tex]\( Rr \)[/tex], which we cross in a Punnett square.
3. Fill Out the Punnett Square:
- Each parent can pass on one allele to the offspring. We consider all combinations of these alleles:
- The possible offspring combinations are: [tex]\( RR \)[/tex], [tex]\( Rr \)[/tex], [tex]\( Rr \)[/tex], and [tex]\( rr \)[/tex].
4. Phenotype Analysis:
- Red Flowers: The genotypes [tex]\( RR \)[/tex], [tex]\( Rr \)[/tex], and [tex]\( Rr \)[/tex] produce red flowers. So, three out of the four possible combinations result in red-flowering plants.
- White Flowers: The genotype [tex]\( rr \)[/tex] results in white flowers. There is one such combination.
5. Calculate the Ratio:
- Count the number of each phenotype:
- Red-flowering plants: 3 combinations (RR, Rr, Rr)
- White-flowering plants: 1 combination (rr)
- The ratio of red-to-white flowering plants is 3:1.
Therefore, the horticulturalist can expect to see a 3:1 ratio of red-to-white flowering plants in the phenotypes of the F2 generation.
The expected ratio of red- to white-flowering plants in the F2 generation is c. 3 red: 1 white.
Let's analyze the Punnett square:
Genotypes in F1: The F1 generation consists of Rr individuals (one dominant R allele and one recessive r allele). This is because the horticulturalist crossed two geraniums from the F1 generation.
F1 Cross: When you cross two Rr individuals, you get the following genotypes in the F2 generation:
- RR (1/4)
- Rr (1/2)
- rr (1/4)
Phenotypes:
- Red flowers: RR and Rr individuals will have red flowers because they carry at least one dominant R allele. This accounts for 3/4 of the offspring.
- White flowers: Only rr individuals will have white flowers. This accounts for 1/4 of the offspring.
Therefore, the expected ratio of red to white flowering plants is 3:1, which corresponds to option C.
The complete question is:
A horticulturist wants to produce geraniums with specific characteristics She knows that the trait of red flowers is governed by the allele R(RR and Rr) and the trail of white flowers is governed by the allele r(rr) The horticulturalist crosses two geraniums from the F1 generation. The Punnett square demonstrates this cross. Which ratio of red- to white-flowering plants would she expect to see in the phenotypes of the F2 generation?
a. 1 red: 3 white
b. 2 red 2 white
c. 3 red 1 white
d. all red
