Biology

To solve for the frequency of the dominant allele when the frequency of the dominant phenotype is given, we can use the Hardy-Weinberg principle.

 

Step 1: Hardy-Weinberg equation

The Hardy-Weinberg principle states that the frequency of genotypes in a population can be represented as:

Where:

1. is the frequency of the homozygous dominant genotype (AA),

2. is the frequency of the heterozygous genotype (Aa),

3. is the frequency of the homozygous recessive genotype (aa),

4. is the frequency of the dominant allele,

5. is the frequency of the recessive allele.

 

Step 2: Frequency of the dominant phenotype

The dominant phenotype includes both the homozygous dominant (AA) and heterozygous (Aa) individuals. So, the frequency of the dominant phenotype is:

 

We are given that the frequency of the dominant phenotype is 0.36. Therefore:

 

Step 3: Solve for the dominant allele frequency

We know that p + q = 1, so q = 1 - p. Now, we can substitute this into the equation for the dominant phenotype:

 

Expanding and simplifying:

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