Answer :
To solve this problem, we'll explore the genetic cross between a true-breeding red-flowered geranium and a true-breeding white-flowered geranium.
Here’s how you break it down:
1. Understanding the Genotype:
- The trait for red flowers is governed by the dominant allele "R" (either "RR" or "Rr" results in red flowers).
- The trait for white flowers is governed by the recessive allele "r" (only "rr" results in white flowers).
- A true-breeding organism has two identical alleles for a trait. Therefore, the true-breeding red-flowered geranium must have the genotype "RR", and the true-breeding white-flowered geranium must have the genotype "rr".
2. Setting Up the Cross:
- We're crossing a red-flowered geranium ("RR") with a white-flowered geranium ("rr").
- Each parent contributes one allele to the offspring.
3. Constructing the Punnett Square:
- The red-flowered parent with genotype "RR" can only pass on the "R" allele.
- The white-flowered parent with genotype "rr" can only pass on the "r" allele.
4. Filling in the Punnett Square:
- Each cell within the Punnett square represents a possible genetic combination in the offspring.
- As the only possible combination from "R" (from "RR") and "r" (from "rr") is "Rr", all offspring will have the genotype "Rr".
Based on this cross, all offspring will have the genotype "Rr", which results in red flowers. The Punnett square will look like this:
| Parent 1\Parent 2 | R | R |
|-------------------|---|---|
| r | Rr| Rr|
| r | Rr| Rr|
All the offspring (represented in the table cells) will be "Rr," indicating that they will all display the red flower phenotype due to the presence of the dominant "R" allele.
Therefore, the best description for this cross is a Punnett square where all combinations are "Rr", indicating red flowers for all offspring.
Here’s how you break it down:
1. Understanding the Genotype:
- The trait for red flowers is governed by the dominant allele "R" (either "RR" or "Rr" results in red flowers).
- The trait for white flowers is governed by the recessive allele "r" (only "rr" results in white flowers).
- A true-breeding organism has two identical alleles for a trait. Therefore, the true-breeding red-flowered geranium must have the genotype "RR", and the true-breeding white-flowered geranium must have the genotype "rr".
2. Setting Up the Cross:
- We're crossing a red-flowered geranium ("RR") with a white-flowered geranium ("rr").
- Each parent contributes one allele to the offspring.
3. Constructing the Punnett Square:
- The red-flowered parent with genotype "RR" can only pass on the "R" allele.
- The white-flowered parent with genotype "rr" can only pass on the "r" allele.
4. Filling in the Punnett Square:
- Each cell within the Punnett square represents a possible genetic combination in the offspring.
- As the only possible combination from "R" (from "RR") and "r" (from "rr") is "Rr", all offspring will have the genotype "Rr".
Based on this cross, all offspring will have the genotype "Rr", which results in red flowers. The Punnett square will look like this:
| Parent 1\Parent 2 | R | R |
|-------------------|---|---|
| r | Rr| Rr|
| r | Rr| Rr|
All the offspring (represented in the table cells) will be "Rr," indicating that they will all display the red flower phenotype due to the presence of the dominant "R" allele.
Therefore, the best description for this cross is a Punnett square where all combinations are "Rr", indicating red flowers for all offspring.
