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. Here’s a step-by-step breakdown:

### Step 1: Understand the Genetic Background
The size of the seed grain in peas is determined by a specific gene, often denoted as the "B" gene. This gene has two alleles: one dominant (B) and one recessive (b).

**Hint:** Identify the alleles involved in the trait being studied.

### Step 2: Analyze the Dominance Relationship
- When the genotype is homozygous dominant (BB), the seeds are round and large due to sufficient starch production.
- When the genotype is homozygous recessive (bb), the seeds are wrinkled and smaller due to insufficient starch production.
- In the heterozygous condition (Bb), one might expect the dominant trait to fully express, resulting in large seeds. However, the seeds are of intermediate size.

**Hint:** Consider how the dominant and recessive alleles express themselves in different genotypes.

### Step 3: Identify the Type of Dominance
Since the heterozygous condition (Bb) results in an intermediate phenotype rather than the dominant phenotype (large seeds), this indicates that the dominant allele does not completely mask the effect of the recessive allele. This phenomenon is known as incomplete dominance.

**Hint:** Determine if the heterozygous condition shows a blend or intermediate trait rather than the dominant trait.

### Step 4: Conclusion
Based on the analysis, the size of the seed grain in pea is an example of **incomplete dominance**. Therefore, the correct answer to the question is:

**Answer:** B) Incomplete dominance