In a monohybrid cross, the genotypic ratio of `"F"_(2)` is:

Options

A. `3:1`
B. `1:2:1`
C. `1:1`
D. `9:3:3:1`

Answer

To find the genotypic ratio of the F2 generation in a monohybrid cross, we can follow these steps:

### Step 1: Understand the Monohybrid Cross
A monohybrid cross involves a single trait and typically examines the inheritance of one gene with two alleles. For example, let's consider the trait for plant height where "T" (tall) is dominant and "t" (dwarf) is recessive.

### Step 2: Define the Parental Generation (P Generation)
In our example, we have:
- Homozygous tall plants: TT (dominant)
- Homozygous dwarf plants: tt (recessive)

### Step 3: Determine the F1 Generation
When we cross the P generation (TT x tt), all offspring in the F1 generation will be heterozygous (Tt) and exhibit the dominant phenotype (tall).

### Step 4: Self-Fertilize the F1 Generation
To obtain the F2 generation, we self-fertilize the F1 generation (Tt x Tt).

### Step 5: Create a Punnett Square
We can use a Punnett square to visualize the possible genotypes of the F2 generation:
```
T t
-------------
T | TT | Tt |
-------------
t | Tt | tt |
```

### Step 6: Analyze the Results
From the Punnett square, we see the following genotypes:
- 1 TT (homozygous dominant)
- 2 Tt (heterozygous)
- 1 tt (homozygous recessive)

### Step 7: Determine the Genotypic Ratio
The genotypic ratio of the F2 generation is:
- 1 TT : 2 Tt : 1 tt

Thus, the genotypic ratio is **1:2:1**.

### Final Answer
The genotypic ratio of F2 in a monohybrid cross is **1:2:1**.

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