A cross between two tall plants resulted in offspring having few dwarf plants. What would be the genotypes of both the plants ?

Options

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

Explanation

To determine the genotypes of the two tall plants that resulted in offspring with a few dwarf plants, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Traits**:
- In this scenario, we have two traits: tall (dominant) and dwarf (recessive). We denote tall as "T" and dwarf as "t".

2. **Understanding the Offspring**:
- The offspring from the cross of two tall plants include some dwarf plants. This indicates that the tall plants must carry the recessive allele for dwarfness (t).

3. **Determine Possible Genotypes**:
- The possible genotypes for the tall plants can be:
- Homozygous dominant (TT) - would produce only tall offspring.
- Heterozygous (Tt) - would produce both tall and dwarf offspring.

4. **Use a Punnett Square**:
- Since we observe dwarf plants in the offspring, we conclude that both parent plants must be heterozygous (Tt).
- We can set up a Punnett square to visualize the cross:
```
T | t
----------------
T | TT | Tt
----------------
t | Tt | tt
```

5. **Analyze the Results**:
- From the Punnett square, we see the following genotypic ratios:
- 1 TT (tall)
- 2 Tt (tall)
- 1 tt (dwarf)
- This gives us a phenotypic ratio of 3 tall plants to 1 dwarf plant.

6. **Conclusion**:
- Therefore, the genotypes of both tall parent plants are Tt (heterozygous).

### Final Answer:
The genotypes of both tall plants are Tt (heterozygous).

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