A dihybrid for qualitative trait is crossed with homozygous recessive individual of its type, the phenotypic ratio is

Options

A. `1:2:1`
B. `3:1`
C. ` 1:1:1:1`
D. `9:3:3:1`

Answer

To solve the question about the phenotypic ratio resulting from a dihybrid cross with a homozygous recessive individual, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Cross**:
- A dihybrid organism has two traits, each with two alleles. For example, let's denote the traits as R (dominant) and r (recessive) for the first trait, and Y (dominant) and y (recessive) for the second trait.
- The dihybrid organism can be represented as RrYy.
- The homozygous recessive individual will be represented as rryy.

2. **Set Up the Gametes**:
- The dihybrid organism (RrYy) can produce four types of gametes: RY, Ry, rY, and ry.
- The homozygous recessive individual (rryy) can only produce one type of gamete: ry.

3. **Perform the Cross**:
- When we cross RrYy with rryy, we can set up a Punnett square to visualize the offspring.
- The gametes from RrYy (RY, Ry, rY, ry) will be placed on one side, and the gametes from rryy (ry) will be placed on the other side.

4. **Fill in the Punnett Square**:
- The combinations will be:
- RY x ry = RrYy (Round and Yellow)
- Ry x ry = Rryy (Round and Green)
- rY x ry = rrYy (Wrinkled and Yellow)
- ry x ry = rryy (Wrinkled and Green)

5. **Determine the Phenotypes**:
- From the combinations, we can identify the phenotypes:
- 1 RrYy (Round and Yellow)
- 1 Rryy (Round and Green)
- 1 rrYy (Wrinkled and Yellow)
- 1 rryy (Wrinkled and Green)

6. **Calculate the Phenotypic Ratio**:
- The resulting phenotypic ratio from the cross is:
- Round and Yellow : Round and Green : Wrinkled and Yellow : Wrinkled and Green
- This gives us a ratio of 1:1:1:1.

### Final Answer:
The phenotypic ratio of the offspring from this dihybrid cross with a homozygous recessive individual is **1:1:1:1**.