In a dihybrid cross where two parents differ in two pairs of contrasting traits like seed colour yellow (YY) and seed colour green (yy) with seed shape round (RR) and seed shape wrinkled (rr), the number of green coloured seeds (yy) among sixteen products of `F_(2)` generation will be

Options

A. 2
B. 4
C. 6
D. 8

Answer

To solve the problem of determining the number of green-colored seeds (yy) among sixteen products of the F2 generation in a dihybrid cross, we can follow these steps:

### Step 1: Understand the Dihybrid Cross
In a dihybrid cross, we are looking at two traits that are inherited independently. In this case, the traits are:
- Seed color: Yellow (YY) and Green (yy)
- Seed shape: Round (RR) and Wrinkled (rr)

### Step 2: Determine the Genotypes of the Parents
The parental generation consists of:
- One parent with genotype YYRR (homozygous yellow and round)
- The other parent with genotype yyrr (homozygous green and wrinkled)

### Step 3: Create the F1 Generation
When we cross these two parents (YYRR x yyrr), all offspring (F1 generation) will have the genotype YyRr. This means they will all be yellow and round since yellow (Y) and round (R) are dominant traits.

### Step 4: Create the F2 Generation
To create the F2 generation, we need to cross two F1 individuals (YyRr x YyRr). We can use a Punnett square to determine the genotypes of the F2 generation.

### Step 5: Set Up the Punnett Square
The gametes from each parent (YyRr) can be:
- YR
- Yr
- yR
- yr

Setting up a 4x4 Punnett square with these gametes will give us 16 combinations in the F2 generation.

### Step 6: Count the Genotypes
After filling out the Punnett square, we can count the genotypes:
- YYRR: 1
- YYRr: 2
- YyRR: 2
- YyRr: 4
- YYrr: 1
- Yyrr: 2
- yyRR: 1
- yyRr: 2
- yyrr: 1

### Step 7: Identify the Green Seeds
Green seeds will have the genotype "yy" regardless of the shape. From our counts:
- yyRR: 1
- yyRr: 2
- yyrr: 1

Adding these up gives us:
1 (yyRR) + 2 (yyRr) + 1 (yyrr) = 4 green seeds.

### Step 8: Conclusion
Thus, the number of green-colored seeds (yy) among the sixteen products of the F2 generation is **4**.

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