The size of the seed grain in pea is an example of :

Options

A. Complete Dominance
B. Incomplete dominance
C. Multiple alleles
D. Pleiotropism

Answer

To solve the question regarding the size of the seed grain in pea, we need to analyze the genetic principles involved.

### Step-by-Step Solution:

1. **Understanding the Traits**: The question refers to the size of the seed grain in peas, which can either be round or wrinkled. The round seed trait is dominant, while the wrinkled seed trait is recessive.

2. **Identifying the Alleles**: The dominant allele for round seeds is represented as "B" (capital B), and the recessive allele for wrinkled seeds is represented as "b" (small b).

3. **Genotype Combinations**:
- Homozygous dominant (BB): Produces round seeds.
- Homozygous recessive (bb): Produces wrinkled seeds.
- Heterozygous (Bb): Also produces round seeds because the dominant trait masks the recessive trait.

4. **Exploring Incomplete Dominance**: In cases where the dominant allele does not completely mask the recessive allele, we observe an intermediate phenotype. This is known as incomplete dominance.

5. **Analyzing the Seed Size**: The question implies that when both alleles are present (Bb), the seed grain size is intermediate, which means it is neither fully round nor fully wrinkled. This indicates that the dominant allele (B) is not fully expressing itself over the recessive allele (b).

6. **Conclusion**: Since the seed grain size shows an intermediate phenotype, this is an example of **incomplete dominance**.

### Final Answer:
The size of the seed grain in pea is an example of **incomplete dominance**.

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