How many given characters of garden pea express when the factor are homozygous only ?
Terminal flower, Green seed, Yellow pod, Constricted pod, Violet petals, Dwarf stem

Options

A. four
B. Five
C. Six
D. One

Answer

To determine how many of the given characters of garden pea express only when the factors are homozygous, we need to identify which traits are recessive. According to Mendel's principles of inheritance, recessive traits can only be expressed when both alleles are the same (homozygous).

### Step-by-Step Solution:

1. **List the Given Characters**:
- Terminal flower
- Green seed
- Yellow pod
- Constricted pod
- Violet petals
- Dwarf stem

2. **Identify Dominant and Recessive Traits**:
- According to Mendel's findings:
- **Height of plant**: Tall (dominant) and Dwarf (recessive)
- **Seed color**: Yellow (dominant) and Green (recessive)
- **Pod color**: Green (dominant) and Yellow (recessive)
- **Pod shape**: Inflated (dominant) and Constricted (recessive)
- **Flower color**: Violet (dominant) and White (recessive)
- **Flower position**: Axial (dominant) and Terminal (recessive)

3. **Classify the Given Characters**:
- **Terminal flower**: Recessive
- **Green seed**: Recessive
- **Yellow pod**: Recessive
- **Constricted pod**: Recessive
- **Violet petals**: Dominant
- **Dwarf stem**: Recessive

4. **Count the Recessive Traits**:
- From the classification:
- Terminal flower: Recessive
- Green seed: Recessive
- Yellow pod: Recessive
- Constricted pod: Recessive
- Dwarf stem: Recessive
- Total recessive traits = 5

5. **Conclusion**:
- The number of given characters that express only when the factors are homozygous is **5**.

### Final Answer:
**5 characters express when the factors are homozygous only.**