What shall be the genotypic ratio in `F_(2)` generation of monohybrid cross?

Options

A. `3:1`
B. `1:2:1`
C. `1:1:1`
D. None of the above

Answer

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

### Step-by-Step Solution:

1. **Understanding the Monohybrid Cross**:
- A monohybrid cross involves a single trait that is being studied, typically represented by two alleles (e.g., T for tall and t for dwarf).

2. **Setting Up the Parental Generation (P)**:
- Let's assume we have two parents: one homozygous tall (TT) and one homozygous dwarf (tt).

3. **F1 Generation**:
- When these parents are crossed (TT x tt), all offspring in the F1 generation will be heterozygous (Tt). This is because they inherit one allele from each parent.

4. **Selfing the F1 Generation**:
- To obtain the F2 generation, we self-cross the F1 individuals (Tt x Tt).

5. **Gamete Formation**:
- The gametes produced by the F1 generation (Tt) can be T and t. Therefore, when we set up the Punnett square for Tt x Tt, we have:
- T from the first Tt and T from the second Tt
- T from the first Tt and t from the second Tt
- t from the first Tt and T from the second Tt
- t from the first Tt and t from the second Tt

6. **Punnett Square**:
- The Punnett square will look like this:

```
T t
----------------
T | TT | Tt |
----------------
t | Tt | tt |
----------------
```

7. **Genotypic Outcomes**:
- From the Punnett square, we can see the genotypes of the F2 generation:
- 1 TT (homozygous tall)
- 2 Tt (heterozygous tall)
- 1 tt (homozygous dwarf)

8. **Calculating the Genotypic Ratio**:
- The genotypic ratio from the F2 generation is:
- 1 TT : 2 Tt : 1 tt
- Therefore, the genotypic ratio is **1 : 2 : 1**.

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

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