The recombinant phenotypic and genotypic ratio in `F_2` obtained from parental cross having genotypes TTRR x ttrr will be

Options

A. `{:("Phenotypic ratio","Genotypic ratio"),(9:3:3:1,1:2:2:4:1:2:1:2:1):}`
B. `{:("Phenotypic ratio","Genotypic ratio"),(3:3,1:2:3):}`
C. `{:("Phenotypic ratio","Genotypic ratio"),(3:1,1:2:1):}`
D. `{:("Phenotypic ratio","Genotypic ratio"),(3:3,1:2:1:2):}`

Answer

To solve the problem of determining the recombinant phenotypic and genotypic ratios in the F2 generation from the parental cross TTRR x ttrr, we will follow these steps:

### Step 1: Identify the Parental Genotypes
The parental genotypes are:
- Parent 1: TTRR (homozygous dominant for both traits)
- Parent 2: ttrr (homozygous recessive for both traits)

### Step 2: Determine the F1 Generation
When we cross TTRR with ttrr, all offspring in the F1 generation will be heterozygous for both traits:
- F1 Genotype: TtRr
- F1 Phenotype: Dominant phenotype (since both traits are dominant)

### Step 3: Perform a Dihybrid Cross for F2 Generation
Next, we will perform a dihybrid cross of the F1 generation (TtRr x TtRr) to obtain the F2 generation.

Using a Punnett square for a dihybrid cross, we can determine the genotypes and phenotypes of the F2 generation.

### Step 4: Determine the Genotypic Ratio in F2
The genotypic ratio for a typical dihybrid cross (TtRr x TtRr) is:
- 1 TT RR
- 2 Tt RR
- 2 TT rr
- 4 Tt Rr
- 1 tt RR
- 2 tt Rr
- 1 tt rr

This results in the genotypic ratio:
- 1:2:2:4:1:2:1

### Step 5: Identify Parental and Recombinant Types
From the F2 generation, the parental types are:
- Parental Phenotypes:
- Capital T Capital R (from TTRR)
- Small t Small r (from ttrr)

The recombinant phenotypes are:
- Tt rr (T phenotype with r phenotype)
- tt Rr (t phenotype with R phenotype)

### Step 6: Determine the Recombinant Phenotypic Ratio
The recombinant phenotypic ratio (excluding parental types) will be:
- 3 (Tt rr) : 3 (tt Rr)

### Step 7: Determine the Recombinant Genotypic Ratio
The recombinant genotypic ratio (excluding parental types) will be:
- 1 Tt rr : 2 Tt Rr : 1 tt Rr

### Final Result
Thus, the recombinant phenotypic ratio is 3:3 (or 1:1), and the recombinant genotypic ratio is 1:2:1.

### Summary
- **Recombinant Phenotypic Ratio:** 3:3 (or 1:1)
- **Recombinant Genotypic Ratio:** 1:2:1

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