Answer :
To solve the question about the expected ratio of red-to-white flowering geraniums, let's use the information given in the Punnett square to understand the inheritance of the flower color trait.
1. Understanding Flower Color Genetics:
- Red flowers are determined by the presence of at least one 'R' allele (RR or Rr).
- White flowers occur only when two recessive 'r' alleles are present (rr).
2. Analyzing the Punnett Square:
The given Punnett square for crossing two F1 geraniums shows the possible genotypes:
- Top: R and r alleles from one parent
- Side: R and r alleles from the other parent
3. Genotype Combinations in the Punnett Square:
- RR: A combination where both alleles are dominant, resulting in red flowers.
- Rr: A combination where one dominant and one recessive allele result in red flowers (since the dominant 'R' allele expresses the red trait).
- rr: A combination with both recessive alleles, resulting in white flowers.
4. Counting Phenotypes in the F2 Generation:
- Red flowering outcomes (RR and Rr): There are three possible combinations—RR, Rr, and another Rr.
- White flowering outcome (rr): There is one possible combination—rr.
5. Phenotype Ratio Calculation:
- Red plants: 3 (from genotypes RR, Rr, Rr)
- White plants: 1 (from genotype rr)
6. Conclusion:
- The expected phenotype ratio of red-to-white flowering geraniums in the F2 generation is 3 red: 1 white.
Therefore, the horticulturalist should expect to see a 3:1 ratio of red-to-white flowering plants in the F2 generation of geraniums.
1. Understanding Flower Color Genetics:
- Red flowers are determined by the presence of at least one 'R' allele (RR or Rr).
- White flowers occur only when two recessive 'r' alleles are present (rr).
2. Analyzing the Punnett Square:
The given Punnett square for crossing two F1 geraniums shows the possible genotypes:
- Top: R and r alleles from one parent
- Side: R and r alleles from the other parent
3. Genotype Combinations in the Punnett Square:
- RR: A combination where both alleles are dominant, resulting in red flowers.
- Rr: A combination where one dominant and one recessive allele result in red flowers (since the dominant 'R' allele expresses the red trait).
- rr: A combination with both recessive alleles, resulting in white flowers.
4. Counting Phenotypes in the F2 Generation:
- Red flowering outcomes (RR and Rr): There are three possible combinations—RR, Rr, and another Rr.
- White flowering outcome (rr): There is one possible combination—rr.
5. Phenotype Ratio Calculation:
- Red plants: 3 (from genotypes RR, Rr, Rr)
- White plants: 1 (from genotype rr)
6. Conclusion:
- The expected phenotype ratio of red-to-white flowering geraniums in the F2 generation is 3 red: 1 white.
Therefore, the horticulturalist should expect to see a 3:1 ratio of red-to-white flowering plants in the F2 generation of geraniums.
