In a typical monohybrid coss % of `F_(2)` resembling the `F_(1)` phenotypically

Options

A. 100
B. 75
C. 50
D. 25

Answer

To solve the question regarding the percentage of F2 resembling the F1 phenotypically in a typical monohybrid cross, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Monohybrid Cross**:
In a monohybrid cross, we typically examine the inheritance of a single trait. For example, let's consider a cross between tall (T) and dwarf (t) pea plants.

2. **Determine the Genotypes of the Parents**:
The parental generation (P) consists of homozygous tall (TT) and homozygous dwarf (tt) plants.

3. **F1 Generation**:
When we cross TT (tall) with tt (dwarf), all offspring in the F1 generation will be heterozygous (Tt) and will exhibit the dominant phenotype, which is tall.

4. **Selfing the F1 Generation**:
To produce the F2 generation, we perform self-fertilization of the F1 plants (Tt x Tt).

5. **Punnett Square Analysis**:
We can set up a Punnett square to visualize the possible genotypes of the F2 generation:
```
T t
---------
T | TT | Tt |
---------
t | Tt | tt |
```

6. **Genotype Ratios**:
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)

This gives us a genotype ratio of 1:2:1.

7. **Phenotype Ratios**:
The phenotypic ratio based on the genotypes is:
- Tall (TT and Tt): 3
- Dwarf (tt): 1

Thus, the phenotypic ratio is 3:1.

8. **Percentage Resembling F1 Phenotypically**:
Since the F1 generation is all tall, we calculate the percentage of F2 that resembles F1 phenotypically (tall):
- Tall plants in F2 = 3 out of 4 (75%)
- Dwarf plants in F2 = 1 out of 4 (25%)

Therefore, the percentage of F2 resembling F1 phenotypically is 75%.

### Final Answer:
In a typical monohybrid cross, the percentage of F2 resembling the F1 phenotypically is **75%**.

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