When Mendel self hybridised 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) and the segregation of dominant and recessive traits, we can follow these steps:

### Step 1: Understand the Genotypes Involved
Mendel's F1 plants (RrYy) represent a dihybrid cross where:
- Rr represents the round (R) and wrinkled (r) seed shape.
- Yy represents the yellow (Y) and green (y) seed color.

### Step 2: Determine the Possible Gametes
From the genotype RrYy, the possible gametes that can be produced are:
- RY (Round Yellow)
- Ry (Round Green)
- rY (Wrinkled Yellow)
- ry (Wrinkled Green)

### Step 3: Set Up a Punnett Square
To visualize the offspring from the self-hybridization of RrYy, we can set up a Punnett square with the gametes:
```
RY Ry rY ry
-----------------------
RY | RRY Y RRYy RrYy Rryy
-----------------------
Ry | RRYy Rryy RrYy Rryy
-----------------------
rY | RrYy Rryy rrYY rrYy
-----------------------
ry | RrYy Rryy rrYy rryy
```

### Step 4: Calculate the Phenotypic Ratios
From the Punnett square, we can count the phenotypes:
- Round Yellow (R_Y): 9
- Round Green (R_y): 3
- Wrinkled Yellow (r_Y): 3
- Wrinkled Green (r_y): 1

### Step 5: Combine Ratios for One Trait
If we focus on the yellow and green traits, we can combine the round and wrinkled categories:
- Yellow (R_Y + r_Y): 9 + 3 = 12
- Green (R_y + r_y): 3 + 1 = 4

Thus, the ratio of yellow to green is 12:4, which simplifies to 3:1.

### Conclusion
The dominant and recessive traits of one character segregate in a **3:1 ratio** when Mendel self-hybridized the F1 plants (RrYy).

**Final Answer: Option D (3:1 ratio)**

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