Answer :
To find the expected ratio of red-to-white flowering plants in the F2 generation, let's walk through the situation step-by-step.
1. Identify the Alleles:
- The trait for red flowers is indicated by the allele R. Plants with genotypes RR or Rr will produce red flowers.
- The trait for white flowers is indicated by the allele r. Only plants with genotype rr will produce white flowers.
2. Setting Up the Cross:
- We are considering a cross between two geraniums from the F1 generation. These are typically heterozygous (Rr), meaning each parent has one allele for red flowers (R) and one allele for white flowers (r).
3. Using the Punnett Square:
- The Punnett square for the cross of two Rr (red flower) plants is set up as follows:
```
| R | r |
-----------------
R | RR | Rr |
-----------------
r | Rr | rr |
```
- From this Punnett square, we can identify four possible genotype combinations for the offspring:
- RR
- Rr
- Rr
- rr
4. Determine Phenotypes:
- The genotypes RR and Rr both result in red-flowering plants.
- The genotype rr results in white-flowering plants.
5. Count and Ratio:
- Count the occurrences of each phenotype based on the genotypes:
- There are 3 genotypes that result in red flowers (RR, Rr, and Rr).
- There is 1 genotype that results in white flowers (rr).
- Therefore, the ratio of red to white flowering plants in the F2 generation is 3:1.
So, the expected ratio of red-to-white flowering plants in the F2 generation is 3:1.
1. Identify the Alleles:
- The trait for red flowers is indicated by the allele R. Plants with genotypes RR or Rr will produce red flowers.
- The trait for white flowers is indicated by the allele r. Only plants with genotype rr will produce white flowers.
2. Setting Up the Cross:
- We are considering a cross between two geraniums from the F1 generation. These are typically heterozygous (Rr), meaning each parent has one allele for red flowers (R) and one allele for white flowers (r).
3. Using the Punnett Square:
- The Punnett square for the cross of two Rr (red flower) plants is set up as follows:
```
| R | r |
-----------------
R | RR | Rr |
-----------------
r | Rr | rr |
```
- From this Punnett square, we can identify four possible genotype combinations for the offspring:
- RR
- Rr
- Rr
- rr
4. Determine Phenotypes:
- The genotypes RR and Rr both result in red-flowering plants.
- The genotype rr results in white-flowering plants.
5. Count and Ratio:
- Count the occurrences of each phenotype based on the genotypes:
- There are 3 genotypes that result in red flowers (RR, Rr, and Rr).
- There is 1 genotype that results in white flowers (rr).
- Therefore, the ratio of red to white flowering plants in the F2 generation is 3:1.
So, the expected ratio of red-to-white flowering plants in the F2 generation is 3:1.
