In a population of 2000 individuals, 500 belong to genotype AA, 500 to aa and remaining to Aa.. What is the frequency of allele A in this population?

Options

A. 0.3
B. 0.5
C. 0.6
D. 0.25

Answer

To find the frequency of allele A in the given population, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the total population and genotypes**:
- Total individuals = 2000
- Individuals with genotype AA = 500
- Individuals with genotype aa = 500
- Individuals with genotype Aa = Total individuals - (AA + aa) = 2000 - (500 + 500) = 1000

2. **Determine the number of alleles**:
- Each individual has 2 alleles. Therefore, the total number of alleles in the population = 2000 individuals × 2 alleles/individual = 4000 alleles.

3. **Calculate the contribution of each genotype to allele A**:
- Each AA individual contributes 2 alleles A:
- Contribution from AA = 500 individuals × 2 = 1000 alleles A
- Each Aa individual contributes 1 allele A:
- Contribution from Aa = 1000 individuals × 1 = 1000 alleles A
- Individuals with genotype aa do not contribute any alleles A.

4. **Total number of allele A**:
- Total alleles A = Contribution from AA + Contribution from Aa = 1000 + 1000 = 2000 alleles A.

5. **Calculate the frequency of allele A**:
- Frequency of allele A (p) = Total alleles A / Total alleles = 2000 / 4000 = 0.5.

### Final Answer:
The frequency of allele A in this population is **0.5**.