A plant of `F_(1)`-generation has genotype 'AABbCC'. On selfing of this plant, the phenotypic ratio in `F_(2)`-generation will be

Options

A. `3:1`
B. `1:1`
C. `9:3:3:1`
D. `27:9:9:9:3:3:3:1`

Answer

To determine the phenotypic ratio in the F2 generation from a plant with the genotype 'AABbCC', we will follow these steps:

### Step 1: Identify the Genotype of the F1 Generation
The given genotype of the F1 generation is AABbCC. This means:
- A is homozygous dominant (AA)
- B is heterozygous (Bb)
- C is homozygous dominant (CC)

### Step 2: Determine Gametes Produced by F1 Generation
When selfing the F1 plant (AABbCC), we need to determine the gametes it can produce. The possible gametes are formed by taking one allele from each gene:
- From AA, the only allele is A.
- From Bb, the alleles are B and b.
- From CC, the only allele is C.

Thus, the possible gametes are:
- ABC
- ABc
- AbC
- Abc

### Step 3: Set Up a Punnett Square
Now we will set up a Punnett square to cross the gametes. Since the gametes are:
1. ABC
2. ABc
3. AbC
4. Abc

We will cross these gametes with themselves (selfing):
```
ABC ABc AbC Abc
-------------------------------------
ABC | AABBC AABbC AABBC AABbC
ABc | AABbC AABbc AABbC AABbc
AbC | AABBC AABbC AABBC AABbC
Abc | AABbC AABbc AABbC AABbc
```

### Step 4: Determine Phenotypes from the Genotypes
Now we analyze the resulting genotypes:
- AABBC: Phenotype = Dominant
- AABbC: Phenotype = Dominant
- AABbC: Phenotype = Dominant
- AABbc: Phenotype = Dominant
- AABBC: Phenotype = Dominant
- AABbC: Phenotype = Dominant
- AABbc: Phenotype = Dominant

Since A and C are dominant, the only recessive trait comes from the b allele.

### Step 5: Count the Phenotypes
From the Punnett square:
- Dominant phenotype (A_B_C): 12 (AABBC, AABbC, AABBC, AABbC, AABBC, AABbC)
- Recessive phenotype (A_bbC): 4 (AABbc, AABbc)

### Step 6: Calculate the Phenotypic Ratio
The phenotypic ratio is:
- Dominant: Recessive = 12:4 = 3:1

### Conclusion
The phenotypic ratio in the F2 generation from the selfing of the F1 plant with genotype AABbCC is **3:1**.

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