How many plants are dihybrid in `F_(2)` generation of dihybrid cross :-

Options

A. One
B. Two
C. Four
D. Sixteen

Answer

To solve the question of how many plants are dihybrid in the F2 generation of a dihybrid cross, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Dihybrid Cross**: A dihybrid cross involves two traits, each represented by two alleles. For example, we can use R (dominant) and r (recessive) for one trait, and Y (dominant) and y (recessive) for another trait.

2. **Parental Generation (P)**: In the parental generation, we can have two pure lines: one homozygous dominant for both traits (RRYY) and one homozygous recessive for both traits (rryy).

3. **First Filial Generation (F1)**: When we cross these two parents (RRYY x rryy), all offspring in the F1 generation will be heterozygous for both traits (RrYy).

4. **Second Filial Generation (F2)**: To obtain the F2 generation, we cross two F1 individuals (RrYy x RrYy).

5. **Punnett Square for F2 Generation**: When we set up a Punnett square for the dihybrid cross, we will have 16 squares (4 for each trait). The combinations will yield:
- 9 plants with both dominant traits (R_Y_)
- 3 plants with the dominant trait for the first and recessive for the second (R_yy)
- 3 plants with the recessive trait for the first and dominant for the second (rrY_)
- 1 plant with both recessive traits (rryy)

6. **Identify Dihybrid Plants**: Dihybrid plants are those that are heterozygous for both traits (RrYy). From the F2 generation, we can see that there are 4 combinations that are heterozygous for both traits (RrYy).

7. **Conclusion**: Therefore, the number of dihybrid plants in the F2 generation is 4.

### Final Answer:
The number of dihybrid plants in the F2 generation of a dihybrid cross is **4**.