Answer :
Sure! Let's go through the problem step by step to determine the expected ratio of red-to-white flowering plants in the F2 generation of geraniums.
1. Understanding Alleles and Phenotypes:
- The trait for red flowers is controlled by the allele [tex]\( R \)[/tex]. A plant will have red flowers if its genotype is [tex]\( RR \)[/tex] or [tex]\( Rr \)[/tex]. Therefore, both [tex]\( RR \)[/tex] and [tex]\( Rr \)[/tex] result in red flowering plants.
- The trait for white flowers is controlled by the allele [tex]\( r \)[/tex]. A plant will have white flowers only if its genotype is [tex]\( rr \)[/tex].
2. Setting Up the Cross:
- We are given that the horticulturalist crosses two geraniums from the F1 generation, both with genotype [tex]\( Rr \)[/tex]. This means each parent plant can pass on either an [tex]\( R \)[/tex] or an [tex]\( r \)[/tex] allele.
3. Creating the Punnett Square:
- We set up a Punnett square to illustrate all possible combinations of alleles that the offspring can inherit from the parent plants:
```
| R | r |
---------------
R | RR | Rr |
---------------
r | Rr | rr |
```
4. Analyzing the Results:
- There are 4 possible outcomes from this cross: [tex]\( RR \)[/tex], [tex]\( Rr \)[/tex], [tex]\( Rr \)[/tex], and [tex]\( rr \)[/tex].
- [tex]\( RR \)[/tex]: Red flowers
- [tex]\( Rr \)[/tex]: Red flowers
- [tex]\( rr \)[/tex]: White flowers
5. Counting the Phenotypes:
- There are 3 cases that result in red flowering plants ([tex]\( RR \)[/tex] and two [tex]\( Rr \)[/tex]).
- There is 1 case that results in white flowering plants ([tex]\( rr \)[/tex]).
6. Determining the Phenotypic Ratio:
- Based on the counts, the expected ratio of red (combination of [tex]\( RR \)[/tex] and [tex]\( Rr \)[/tex]) to white ([tex]\( rr \)[/tex]) flowering plants is 3 red to 1 white.
So, the correct expected ratio of red-to-white flowering plants in the F2 generation is 3 red : 1 white.
1. Understanding Alleles and Phenotypes:
- The trait for red flowers is controlled by the allele [tex]\( R \)[/tex]. A plant will have red flowers if its genotype is [tex]\( RR \)[/tex] or [tex]\( Rr \)[/tex]. Therefore, both [tex]\( RR \)[/tex] and [tex]\( Rr \)[/tex] result in red flowering plants.
- The trait for white flowers is controlled by the allele [tex]\( r \)[/tex]. A plant will have white flowers only if its genotype is [tex]\( rr \)[/tex].
2. Setting Up the Cross:
- We are given that the horticulturalist crosses two geraniums from the F1 generation, both with genotype [tex]\( Rr \)[/tex]. This means each parent plant can pass on either an [tex]\( R \)[/tex] or an [tex]\( r \)[/tex] allele.
3. Creating the Punnett Square:
- We set up a Punnett square to illustrate all possible combinations of alleles that the offspring can inherit from the parent plants:
```
| R | r |
---------------
R | RR | Rr |
---------------
r | Rr | rr |
```
4. Analyzing the Results:
- There are 4 possible outcomes from this cross: [tex]\( RR \)[/tex], [tex]\( Rr \)[/tex], [tex]\( Rr \)[/tex], and [tex]\( rr \)[/tex].
- [tex]\( RR \)[/tex]: Red flowers
- [tex]\( Rr \)[/tex]: Red flowers
- [tex]\( rr \)[/tex]: White flowers
5. Counting the Phenotypes:
- There are 3 cases that result in red flowering plants ([tex]\( RR \)[/tex] and two [tex]\( Rr \)[/tex]).
- There is 1 case that results in white flowering plants ([tex]\( rr \)[/tex]).
6. Determining the Phenotypic Ratio:
- Based on the counts, the expected ratio of red (combination of [tex]\( RR \)[/tex] and [tex]\( Rr \)[/tex]) to white ([tex]\( rr \)[/tex]) flowering plants is 3 red to 1 white.
So, the correct expected ratio of red-to-white flowering plants in the F2 generation is 3 red : 1 white.