A tall true breeding garden pea plant is crossed with a dwarf true breeding garden pea plant. When the `F_(1)` plants were selfed the resulting genotypes were in the ratio of

Options

A. (a) `1:2:1`:: tall heterozygous: tall homozygous : dwarf
B. (b) `3:1::` tall: dwarf
C. (c) `3:1::` dwarf: tall
D. (d) `1:2:1` :: tall homozygous: tall heterozygous: dwarf

Answer

To solve the question regarding the genotypic ratio of the offspring when a tall true breeding garden pea plant is crossed with a dwarf true breeding garden pea plant, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Parent Plants**:
- The tall true breeding garden pea plant is homozygous dominant (TT).
- The dwarf true breeding garden pea plant is homozygous recessive (tt).

2. **Cross the Parent Plants**:
- When we cross these two plants (TT x tt), all offspring in the F1 generation will inherit one allele from each parent.
- The resulting genotype of the F1 generation will be heterozygous (Tt).

3. **Self-Cross the F1 Generation**:
- When F1 plants (Tt) are selfed (Tt x Tt), we can determine the genotypes of the F2 generation using a Punnett square.

4. **Construct a Punnett Square**:
- The gametes from each parent (Tt x Tt) will be:
- Parent 1 (Tt): T, t
- Parent 2 (Tt): T, t
- The Punnett square will look like this:

| | T | t |
|-----|-----|-----|
| **T** | TT | Tt |
| **t** | Tt | tt |

5. **Determine the Genotypic Ratio**:
- From the Punnett square, we can see the genotypes of the offspring:
- 1 TT (homozygous tall)
- 2 Tt (heterozygous tall)
- 1 tt (homozygous dwarf)
- Therefore, the genotypic ratio is 1 TT : 2 Tt : 1 tt.

6. **Conclusion**:
- The resulting genotypes in the F2 generation when the F1 plants are selfed are in the ratio of 1 tall homozygous (TT) : 2 tall heterozygous (Tt) : 1 dwarf (tt).

### Final Answer:
The resulting genotypes were in the ratio of 1 tall homozygous : 2 tall heterozygous : 1 dwarf.

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