Starch gain in pea plant shows
(a) complete dominance
(b) incomplete dominance
(c) co - dominance
(d) epitasis

Options

A. complete dominance
B. incomplete dominance
C. co - dominance
D. epitasis

Answer

To solve the question regarding the starch gain in pea plants, we will analyze the options provided and understand the genetic principles involved.

### Step-by-Step Solution:

1. **Understanding Starch Grain in Pea Plants**:
- The starch grain in pea plants is controlled by specific genes. The dominant allele is represented as 'B' (capital B) and the recessive allele as 'b' (small b).
- The presence of the dominant allele (B) leads to the synthesis of starch, resulting in round and large grains.

2. **Genotype and Phenotype Analysis**:
- **Genotype BB**: Produces a phenotype with large, round starch grains.
- **Genotype bb**: Results in a phenotype with wrinkled grains and less starch synthesis.
- **Genotype Bb**: This is where we need to focus. In this case, the starch synthesis is not fully dominant, leading to an intermediate phenotype.

3. **Identifying the Type of Dominance**:
- **Complete Dominance**: The dominant allele completely masks the effect of the recessive allele. In this case, the phenotype would be either round or wrinkled, but not intermediate.
- **Incomplete Dominance**: The dominant allele does not completely mask the recessive allele, leading to an intermediate phenotype. This is what happens with the Bb genotype, where the starch synthesis is intermediate.
- **Co-Dominance**: Both alleles express equally in the phenotype. This does not apply here as the dominant allele does not fully express alongside the recessive allele.
- **Epistasis**: This involves one gene masking the effect of another gene, which is not the case here.

4. **Conclusion**:
- Based on the analysis, the starch gain in pea plants shows **incomplete dominance**. Therefore, the correct answer is (b) incomplete dominance.

### Final Answer:
(b) incomplete dominance