Select the correct answer.

In a particular species of frogs, black spots are a dominant trait and their absence is a recessive trait. In a population of frogs, 50 are homozygous for the dominant trait, 34 are heterozygous dominant, and 16 show the recessive trait. Which expression is the correct way to calculate the frequency of the dominant allele?

A. [tex]\frac{50}{100}[/tex]
B. [tex]\frac{84}{100}[/tex]
C. [tex]\frac{50}{200}[/tex]
D. [tex]\frac{134}{200}[/tex]
E. [tex]\frac{100}{200}[/tex]



Answer :

To determine the correct expression for calculating the frequency of the dominant allele in a population, you follow these steps:

1. Calculate the total number of alleles: Since each frog has two alleles, multiply the total number of frogs by 2:
[tex]\[ \text{Total alleles} = (50 + 34 + 16) \times 2 = 200 \][/tex]

2. Determine the total number of dominant alleles:
- Each homozygous dominant frog contributes 2 dominant alleles.
- Each heterozygous dominant frog contributes 1 dominant allele.
- Recessive frogs do not contribute any dominant alleles.

Therefore:
[tex]\[ \text{Dominant alleles} = (50 \times 2) + (34 \times 1) = 100 + 34 = 134 \][/tex]

3. Calculate the frequency of the dominant allele:
The frequency is the ratio of dominant alleles to the total number of alleles:
[tex]\[ \text{Frequency of dominant allele} = \frac{\text{Number of dominant alleles}}{\text{Total number of alleles}} = \frac{134}{200} \][/tex]

Thus, the correct expression to calculate the frequency of the dominant allele is:
D. [tex]\(\frac{134}{200}\)[/tex]