In a monohybrid cross the ratio of `F_(2)` true breeding dominant and true breeding recessive would be

Options

A. `50:50`
B. `25:25`
C. `75:25`
D. `25:75`

Answer

To solve the question regarding the ratio of true breeding dominant to true breeding recessive in a monohybrid cross, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Monohybrid Cross**:
- A monohybrid cross involves a single trait with two alleles, one dominant (T) and one recessive (t). For example, let's consider the trait for plant height where 'Tall' (T) is dominant and 'Dwarf' (t) is recessive.

2. **Identify the Parental Generation (P)**:
- The parental generation consists of one homozygous dominant (TT) and one homozygous recessive (tt) plant.
- Parental Cross: TT (Tall) x tt (Dwarf)

3. **Determine the First Filial Generation (F1)**:
- When the parental generation is crossed, all offspring in the F1 generation will be heterozygous (Tt).
- F1 Generation: All offspring are Tt (Tall).

4. **Self the F1 Generation to Obtain F2**:
- To get the F2 generation, we self-cross the F1 plants (Tt x Tt).
- This can be represented in a Punnett square:
```
T t
-----------
T | TT | Tt |
-----------
t | Tt | tt |
```

5. **Analyze the F2 Generation**:
- The genotypes from the Punnett square are:
- TT (homozygous dominant): 1
- Tt (heterozygous): 2
- tt (homozygous recessive): 1
- Therefore, the phenotypic ratio is:
- 3 Tall (TT + Tt) : 1 Dwarf (tt)

6. **Determine the Ratio of True Breeding Dominant to True Breeding Recessive**:
- True breeding dominant (TT) = 1
- True breeding recessive (tt) = 1
- Thus, the ratio of true breeding dominant to true breeding recessive is:
- 1 : 1

### Final Answer:
The ratio of true breeding dominant to true breeding recessive in the F2 generation of a monohybrid cross is **1:1**.

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