Answer :
The expected ratio of red-to-white-flowering geraniums in the F₂ generation is 3:1.
The horticulturalist crosses two heterozygous F₁ (Rr) geraniums, meaning each parent has one dominant R allele (red) and one recessive r allele (white). The Punnett square for this cross predicts the genetic distribution of the offspring. The possible combinations are RR, Rr, Rr, and rr, meaning 3 out of 4 plants will have at least one dominant R allele, giving red flowers, while 1 out of 4 will have rr, producing white flowers.
Step-by-Step Calculation:
Write the parental genotypes: Rr × Rr.
Create the Punnett square:
R r
R RR Rr
r Rr rr
Determine the phenotypic ratio:
RR (Red) = 1
Rr (Red) = 2
rr (White) = 1
Total plants = 4
Red:White = 3:1
Since dominant alleles mask recessive traits, RR and Rr result in red flowers, while rr results in white flowers. This follows Mendel’s law of segregation, where offspring inherit one allele from each parent, leading to the observed 3:1 ratio.
Complete question:
A horticulturalist wants to produce geraniums with specific characteristics. She knows that the trait of red flowers is governed by the allele R (genotypes RR and Rr), and the trait of white flowers is governed by the allele r (rr).
The horticulturalist crosses two geraniums from the F1 generation. Look at the Punnett square to see this cross: Which ratio of red-to-white-flowering plants would you expect to see in the phenotypes of the F2 generation?
Sure! Let's solve the problem step-by-step.
The horticulturalist wants to understand the inheritance of flower color in geraniums. We are given that the red flower trait is determined by the presence of allele R, irrespective of whether the plant is homozygous (RR) or heterozygous (Rr). Meanwhile, the white flowers appear only if the plant is homozygous recessive (rr).
Here, the horticulturalist is crossing two geraniums from the F1 generation. We have to find out the ratio of red-to-white flowering plants in the F2 generation using a Punnett square.
### Step-by-Step Solution:
1. Identify Parent Genotypes:
- The F1 generation geraniums have the genotype Rr. This means they are heterozygous for the flower color trait (one allele for red, R, and one for white, r).
2. Create the Punnett Square:
- To predict the F2 generation, we cross two Rr individuals.
- The potential gametes from a parent Rr are R and r.
When you set up the Punnett square, here's how it looks:
```
| R | r |
---------------------
R | RR | Rr |
---------------------
r | Rr | rr |
```
3. Determine Offspring Genotypes:
- From this Punnett square, the possible genotypes of the F2 offspring are:
- RR - 1 out of 4
- Rr - 2 out of 4
- rr - 1 out of 4
4. Identify Phenotypes:
- Red-flowering plants (phenotype):
- Genotypes RR and Rr will result in red flowers.
- There are 1 RR and 2 Rr combinations.
- Total = 1 (RR) + 2 (Rr) = 3 red-flowering plants
- White-flowering plants (phenotype):
- Genotype rr will result in white flowers.
- Total = 1 rr
5. Calculate the Ratio:
- The phenotypic ratio of red-to-white plants in the F2 generation is 3 red : 1 white.
So, the expected ratio of red- to white-flowering plants in the phenotypes of the F2 generation is 3 red: 1 white.
The horticulturalist wants to understand the inheritance of flower color in geraniums. We are given that the red flower trait is determined by the presence of allele R, irrespective of whether the plant is homozygous (RR) or heterozygous (Rr). Meanwhile, the white flowers appear only if the plant is homozygous recessive (rr).
Here, the horticulturalist is crossing two geraniums from the F1 generation. We have to find out the ratio of red-to-white flowering plants in the F2 generation using a Punnett square.
### Step-by-Step Solution:
1. Identify Parent Genotypes:
- The F1 generation geraniums have the genotype Rr. This means they are heterozygous for the flower color trait (one allele for red, R, and one for white, r).
2. Create the Punnett Square:
- To predict the F2 generation, we cross two Rr individuals.
- The potential gametes from a parent Rr are R and r.
When you set up the Punnett square, here's how it looks:
```
| R | r |
---------------------
R | RR | Rr |
---------------------
r | Rr | rr |
```
3. Determine Offspring Genotypes:
- From this Punnett square, the possible genotypes of the F2 offspring are:
- RR - 1 out of 4
- Rr - 2 out of 4
- rr - 1 out of 4
4. Identify Phenotypes:
- Red-flowering plants (phenotype):
- Genotypes RR and Rr will result in red flowers.
- There are 1 RR and 2 Rr combinations.
- Total = 1 (RR) + 2 (Rr) = 3 red-flowering plants
- White-flowering plants (phenotype):
- Genotype rr will result in white flowers.
- Total = 1 rr
5. Calculate the Ratio:
- The phenotypic ratio of red-to-white plants in the F2 generation is 3 red : 1 white.
So, the expected ratio of red- to white-flowering plants in the phenotypes of the F2 generation is 3 red: 1 white.
