When a tall plane was self - pollinated, one - fourth of the progeny were dwarf. The genotypes of the parent and dwarf progenies are

Options

A. TT, Tt
B. Tt, tt
C. Tt, Tt
D. TT, TT

Answer

To solve the question regarding the genotypes of the parent and dwarf progenies when a tall plant was self-pollinated, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Problem**: We know that when a tall plant is self-pollinated, one-fourth of the progeny are dwarf. This indicates a genetic ratio that suggests a specific genotype for the parent plant.

2. **Identifying the Tall Plant's Genotype**:
- Tallness (T) is the dominant trait, while dwarfness (t) is the recessive trait.
- If the tall plant were homozygous (TT), all progeny would also be tall (TT), leading to no dwarf plants. Therefore, the tall plant must be heterozygous (Tt).

3. **Self-Pollination of the Tall Plant**:
- When we self-pollinate a heterozygous tall plant (Tt), the possible gametes produced are:
- T (from one parent)
- t (from the other parent)
- The resulting combinations from self-pollination (Tt x Tt) would be:
- TT (tall)
- Tt (tall)
- Tt (tall)
- tt (dwarf)

4. **Calculating the Ratios**:
- From the combinations, we can see that out of 4 progeny:
- 3 are tall (TT, Tt, Tt)
- 1 is dwarf (tt)
- This gives us a ratio of 3 tall to 1 dwarf, which corresponds to the statement that one-fourth of the progeny are dwarf.

5. **Identifying the Genotypes**:
- The genotype of the parent plant is heterozygous tall (Tt).
- The genotype of the dwarf progeny is homozygous recessive (tt).

### Conclusion:
- **Parental Genotype**: Tt (heterozygous tall)
- **Dwarf Progeny Genotype**: tt (homozygous dwarf)