The ratio of F2 generation of a dihybrid cross having pure , monohybrids , dihybrids plants is

Options

A. `1:2:1`
B. `1:2:4`
C. `1:4:8`
D. `1:1:2`

Answer

To solve the question regarding the ratio of the F2 generation of a dihybrid cross involving pure, monohybrid, and dihybrid plants, we can follow these steps:

### Step 1: Understand the Dihybrid Cross
A dihybrid cross involves two traits, each represented by two alleles. For example, let's consider two traits: A (dominant) and a (recessive) for the first trait, and B (dominant) and b (recessive) for the second trait.

### Step 2: Determine the Parental Generation
Assume we have the following parental genotypes:
- Parent 1 (homozygous dominant for both traits): AABB
- Parent 2 (homozygous recessive for both traits): aabb

### Step 3: F1 Generation
When these two parents are crossed, all offspring in the F1 generation will be heterozygous for both traits:
- F1 Generation: AaBb

### Step 4: F2 Generation
To find the F2 generation, we need to perform a self-cross of the F1 generation:
- F1 (AaBb) x F1 (AaBb)

### Step 5: Use a Punnett Square
We can use a 4x4 Punnett square to determine the genotypes of the F2 generation. The combinations will be:
- AABB
- AABb
- AaBB
- AaBb
- Aabb
- Aabb
- aaBB
- aaBb
- aabb

### Step 6: Count the Genotypes
From the Punnett square, we can count the resulting genotypes:
- 1 AABB (homozygous dominant for both traits)
- 2 AABb (heterozygous for the second trait)
- 2 AaBB (heterozygous for the first trait)
- 4 AaBb (heterozygous for both traits)
- 2 Aabb (heterozygous for the first trait, homozygous recessive for the second)
- 1 aabb (homozygous recessive for both traits)

### Step 7: Calculate the Ratio
Now, we can summarize the genotypes:
- 1 AABB : 2 AABb : 2 AaBB : 4 AaBb : 2 Aabb : 1 aabb

The phenotypic ratio for a dihybrid cross in the F2 generation is typically 9:3:3:1 for dominant and recessive traits.

### Final Answer
The ratio of the F2 generation of a dihybrid cross with pure, monohybrid, and dihybrid plants is 9:3:3:1.

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