When Mendel self hydridised the `F_(1)` plants (RrYy) , he found that dominant and recessive traits of one character are segregated in a

Options

A. 9 : 1 ratio
B. 3 : 3 ratio
C. 10 : 6 ratio
D. 3 : 1 ratio

Answer

To solve the question regarding Mendel's self-hybridization of the F1 plants (RrYy), we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Genotype of F1 Plants**:
- The F1 plants are heterozygous for two traits: Round seeds (R) and Yellow seeds (Y). Therefore, their genotype is RrYy.

2. **Set Up the Cross**:
- We will perform a self-cross of the F1 plants, which means we will cross RrYy with RrYy.

3. **Use a Punnett Square**:
- Create a Punnett square to determine the possible genotypes of the offspring. Since we are dealing with two traits, we will create a 4x4 Punnett square.

4. **Fill in the Punnett Square**:
- The gametes from each parent (RrYy) can be RY, Ry, rY, and ry. Fill in the Punnett square with these combinations.

5. **Count the Phenotypes**:
- After filling in the Punnett square, count the phenotypes:
- Round Yellow (RY): 9
- Round Green (Rg): 3
- Wrinkled Yellow (wY): 3
- Wrinkled Green (wg): 1

6. **Determine the Phenotypic Ratio**:
- The phenotypic ratio of the offspring is 9:3:3:1.

7. **Focus on Individual Traits**:
- If we focus on just one trait (e.g., Round vs. Wrinkled), we see:
- Round (R): 9
- Wrinkled (r): 3
- This gives a ratio of 3:1 for the Round to Wrinkled trait.

8. **Focus on the Second Trait**:
- Similarly, for the color of the seeds (Yellow vs. Green):
- Yellow (Y): 9
- Green (y): 3
- This also results in a ratio of 3:1 for Yellow to Green.

9. **Conclusion**:
- The dominant and recessive traits of one character segregate in a ratio of 3:1.

### Final Answer:
The dominant and recessive traits of one character segregate in a ratio of **3:1**.

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