The height of a plant is controlled by three genes. The maximum height in the species is 24 inches , whereas the minimum height in the species is 6 inches . What would be the height of a plant of the same species whose genotype in AaBBcc?

Options

A. 12 inches
B. 15 inches
C. 18 inches
D. 21 inches

Answer

To determine the height of a plant with the genotype AaBBcc, we will analyze the contributions of each allele based on the information provided about maximum and minimum heights.

### Step-by-Step Solution:

1. **Understand the Genetic Control of Height**:
- The height of the plant is controlled by three genes (A, B, and C).
- Each gene has two alleles: one dominant and one recessive.

2. **Identify Maximum and Minimum Heights**:
- Maximum height (all dominant alleles): 24 inches.
- Minimum height (all recessive alleles): 6 inches.

3. **Calculate Contribution of Each Dominant Allele**:
- There are a total of 6 alleles (3 genes × 2 alleles each).
- The contribution of all dominant alleles (6 dominant alleles) results in a height of 24 inches.
- Therefore, the contribution of one dominant allele = 24 inches / 6 = 4 inches.

4. **Calculate Contribution of Each Recessive Allele**:
- The contribution of all recessive alleles (6 recessive alleles) results in a height of 6 inches.
- Therefore, the contribution of one recessive allele = 6 inches / 6 = 1 inch.

5. **Analyze the Given Genotype (AaBBcc)**:
- Genotype AaBBcc consists of:
- A (dominant) contributes: 4 inches
- a (recessive) contributes: 1 inch
- B (dominant) contributes: 4 inches
- B (dominant) contributes: 4 inches
- c (recessive) contributes: 1 inch
- c (recessive) contributes: 1 inch

6. **Calculate Total Height**:
- Total height = Contribution from A + Contribution from a + Contribution from B + Contribution from B + Contribution from c + Contribution from c
- Total height = 4 + 1 + 4 + 4 + 1 + 1 = 15 inches.

### Final Answer:
The height of the plant with genotype AaBBcc is **15 inches**.