In what ratio the parental phenotypes will appear in `F_(2)` generation of dihybrid cross

Options

A. `3//16:3//16`
B. `4//16:4//16`
C. `9//16 :1//16`
D. `12//16 : 4//16`

Answer

To solve the question regarding the ratio of parental phenotypes in the F2 generation of a dihybrid cross, we can follow these steps:

### Step 1: Understand the Dihybrid Cross
A dihybrid cross involves two traits, each represented by two alleles. For this example, we will consider:
- Trait 1: Pod color (Yellow = Y, Green = y)
- Trait 2: Seed shape (Round = R, Wrinkled = r)

### Step 2: Identify the Parental Genotypes
Let’s assume:
- Parent 1 (homozygous dominant): YYRR (Yellow pods and Round seeds)
- Parent 2 (homozygous recessive): yyrr (Green pods and Wrinkled seeds)

### Step 3: Determine the F1 Generation
When these two parents are crossed, all offspring in the F1 generation will be heterozygous:
- F1 Genotype: YyRr (All offspring will have Yellow pods and Round seeds, as both traits are dominant)

### Step 4: Set Up the F2 Generation
To find the F2 generation, we will cross two F1 individuals:
- F1 Cross: YyRr x YyRr

### Step 5: Determine Gametes
Each parent can produce four types of gametes:
- YR, Yr, yR, yr

### Step 6: Create a Punnett Square
Using a 4x4 Punnett square, we can determine the genotypes of the F2 generation:

| | YR | Yr | yR | yr |
|---------|------|------|------|------|
| **YR** | YYRR | YYRr | YyRR | YyRr |
| **Yr** | YYRr | YYrr | YyRr | Yyrr |
| **yR** | YyRR | YyRr | yyRR | yyRr |
| **yr** | YyRr | Yyrr | yyRr | yyrr |

### Step 7: Count the Phenotypes
Now, we will count the phenotypes:
- Yellow pods and Round seeds (Parental phenotype): YYRR, YYRr, YyRR, YyRr (9 combinations)
- Green pods and Wrinkled seeds (Parental phenotype): yyrr (1 combination)

### Step 8: Calculate the Ratio
From the Punnett square:
- Yellow Round (Parental phenotype): 9
- Green Wrinkled (Parental phenotype): 1

Thus, the ratio of parental phenotypes in the F2 generation is:
- **9 (Yellow Round) : 1 (Green Wrinkled)**

### Final Answer
The ratio of parental phenotypes in the F2 generation of a dihybrid cross is **9:1**.

---