Starch gain in pea plant shows

Options

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

Answer

To solve the question about starch grain in pea plants, we need to analyze the genetic control of starch synthesis and how it manifests in the phenotype of the plants. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Genetic Basis
Starch synthesis in pea plants is controlled by a gene that has two alleles, which we can denote as B (dominant) and b (recessive).

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

### Step 2: Analyze Homozygous Conditions
1. In a homozygous dominant condition (BB), the starch grain size is large, leading to round seeds when they mature.
2. In a homozygous recessive condition (bb), the starch grain size is small, resulting in wrinkled seeds.

**Hint:** Consider how different combinations of alleles affect the phenotype.

### Step 3: Examine Heterozygous Condition
In the heterozygous condition (Bb), the size of the starch grain is intermediate. However, the seeds still mature into a round shape.

**Hint:** Look for patterns in how traits are expressed in heterozygous individuals.

### Step 4: Determine the Type of Dominance
Since the heterozygous condition (Bb) results in an intermediate phenotype for starch grain size, this indicates that the dominant allele does not completely mask the effect of the recessive allele. This is characteristic of incomplete dominance.

**Hint:** Recall the definitions of complete dominance, incomplete dominance, co-dominance, and epistasis to identify the correct type.

### Step 5: Identify Pleiotropy
Additionally, this gene exhibits pleiotropy, as it affects both the size of the starch grains and the shape of the seeds.

**Hint:** Consider whether a single gene affects multiple traits, indicating pleiotropy.

### Conclusion
Based on the analysis, the starch grain in pea plants shows **incomplete dominance**.

### Final Answer
The starch grain in pea plants shows **B: incomplete dominance**.