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 dominant, 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 :

Let's analyze the problem step by step to find the correct way to calculate the frequency of the dominant allele in this frog population.

1. Understand the genetic composition:
- Homozygous dominant frogs (50): Each has 2 dominant alleles.
- Heterozygous dominant frogs (34): Each has 1 dominant allele and 1 recessive allele.
- Recessive frogs (16): No dominant alleles, only 2 recessive alleles.

2. Calculate the total number of frogs:
[tex]\( \text{Total population} = 50 + 34 + 16 = 100 \)[/tex]

3. Calculate the total number of alleles in the population:
Since each frog has 2 alleles, the total number of alleles in the population is:
[tex]\( \text{Total alleles} = 100 \times 2 = 200 \)[/tex]

4. Calculate the number of dominant alleles:
- Homozygous dominant frogs contribute: [tex]\( 50 \times 2 = 100 \)[/tex] dominant alleles.
- Heterozygous dominant frogs contribute: [tex]\( 34 \times 1 = 34 \)[/tex] dominant alleles.

So, the total number of dominant alleles is:
[tex]\( 100 + 34 = 134 \)[/tex]

5. Determine the frequency of the dominant allele:
The frequency of the dominant allele is the number of dominant alleles divided by the total number of alleles:
[tex]\[ \text{Frequency of dominant allele} = \frac{134}{200} = 0.67 \][/tex]

Based on this detailed step-by-step analysis, the correct way to calculate the frequency of the dominant allele is:

D. [tex]\(\frac{134}{200}\)[/tex]