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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 :

GinnyAnswer
To determine the frequency of the dominant allele in the frog population, let's outline the steps involved in the calculation:

1. Identify the number of frogs of each genotype:
- Homozygous dominant frogs (BB): [tex]\(50\)[/tex]
- Heterozygous dominant frogs (Bb): [tex]\(34\)[/tex]
- Frogs with the recessive trait (bb): [tex]\(16\)[/tex]

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

3. Determine the number of dominant alleles from each group of frogs:
- Frogs that are homozygous dominant (BB) contribute 2 dominant alleles each. Therefore:
[tex]\[ \text{Dominant alleles from BB} = 50 \times 2 = 100 \][/tex]
- Frogs that are heterozygous dominant (Bb) each contribute 1 dominant allele. Therefore:
[tex]\[ \text{Dominant alleles from Bb} = 34 \times 1 = 34 \][/tex]

4. Calculate the total number of dominant alleles:
[tex]\[ \text{Total dominant alleles} = 100 + 34 = 134 \][/tex]

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

6. Determine the frequency of the dominant allele:
[tex]\[ \text{Frequency of dominant allele} = \frac{\text{Total dominant alleles}}{\text{Total alleles}} = \frac{134}{200} \][/tex]

From the steps above, the correct expression to calculate the frequency of the dominant allele is:

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

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