How many type of genotypes are formed in`F_(2)` Progeny obtained from self - Pollination of a dihybrid of a dihybrid `F_(1)`

Options

A. 9
B. 3
C. 6
D. 1

Answer

To determine how many types of genotypes are formed in the F2 progeny obtained from the self-pollination of a dihybrid F1, 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: seed shape (Round 'R' and Wrinkled 'r') and seed color (Yellow 'Y' and Green 'y').

### Step 2: Determine the F1 Generation
When we cross two true-breeding parents (RRYY x rryy), the F1 generation will be heterozygous for both traits: RrYy. This means that all F1 individuals will have the genotype RrYy.

### Step 3: Self-Pollination of F1 Generation
When the F1 individuals (RrYy) are self-pollinated, we need to consider the possible gametes they can produce. Each F1 plant can produce four types of gametes: RY, Ry, rY, and ry.

### Step 4: Construct a Punnett Square
To find the genotypes of the F2 generation, we can set up a Punnett square using the gametes from the self-pollination of RrYy:

```
RY Ry rY ry
---------------------------
RY | RRYY RRYy RrYY RrYy
---------------------------
Ry | RRYy RRyy RrYy Rryy
---------------------------
rY | RrYY RrYy rrYY rrYy
---------------------------
ry | RrYy Rryy rrYy rryy
```

### Step 5: Count the Genotypes
From the Punnett square, we can list the resulting genotypes:

1. RRYY
2. RRYy
3. RrYY
4. RrYy
5. RRyy
6. Rryy
7. rrYY
8. rrYy
9. rryy

### Conclusion
In total, there are **9 different genotypes** that can be formed in the F2 progeny from the self-pollination of a dihybrid F1.

### Final Answer
The number of different genotypes formed in the F2 progeny is **9**.

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