A cross between a tall plant (TT) and short pea plant (tt) resulted in progeny that were all tall plants because

Options

A. tallness is the dominant trait
B. shortness is the dominant trait
C. tallness is the recessive trait
D. height of pea plant is not governed by gene 'T' or 't'

Explanation

To solve the question regarding the cross between a tall plant (TT) and a short pea plant (tt) resulting in progeny that are all tall, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Genotypes of the Parent Plants:**
- The tall plant has the genotype **TT** (homozygous dominant).
- The short plant has the genotype **tt** (homozygous recessive).

2. **Determine the Gametes Produced by Each Parent:**
- The tall plant (TT) can produce gametes that contain only the dominant allele **T**.
- The short plant (tt) can produce gametes that contain only the recessive allele **t**.

3. **Perform the Cross:**
- When we cross the gametes from both parents, we combine them:
- From the tall plant (TT), we can only get **T**.
- From the short plant (tt), we can only get **t**.
- The possible combinations of alleles in the offspring (F1 generation) will be:
- **T** from the tall plant and **t** from the short plant, resulting in **Tt**.

4. **Analyze the Genotype of the Progeny:**
- All progeny will have the genotype **Tt**. Since **T** is dominant over **t**, the presence of one dominant allele (T) is sufficient to express the tall phenotype.

5. **Conclusion:**
- Since all progeny are **Tt**, they will all exhibit the tall phenotype. This is because tallness (T) is the dominant trait, and the recessive trait (shortness, t) does not manifest in the presence of the dominant allele.

### Final Answer:
The progeny are all tall plants because tallness is the dominant trait (T) and it expresses itself in the presence of the recessive trait (t).

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