Answered

Select the correct answer.

In chickens, a flat single comb is a recessive trait, while the short, thick rose comb is dominant. In a population of chickens, 45 are homozygous for the dominant trait, 30 are heterozygous dominant, and 25 have the recessive trait.

Which expression is the correct way to calculate the frequency of the recessive allele?

A. [tex]\(\frac{80}{100}\)[/tex]
B. [tex]\(\frac{80}{200}\)[/tex]
C. [tex]\(\frac{55}{100}\)[/tex]
D. [tex]\(\frac{55}{200}\)[/tex]
E. [tex]\(\frac{120}{200}\)[/tex]



Answer :

GinnyAnswer
Let's break down the process step by step to find the frequency of the recessive allele in the given population of chickens.

First, let's identify the given numbers:
- The number of chickens that are homozygous dominant (RR) = 45
- The number of chickens that are heterozygous dominant (Rr) = 30
- The number of chickens that are homozygous recessive (rr) = 25

Next, calculate the total number of chickens:
[tex]\[ \text{Total chickens} = 45 + 30 + 25 = 100 \][/tex]

We need to find the total number of recessive alleles in the population. Each homozygous recessive (rr) chicken has 2 recessive alleles, and each heterozygous dominant (Rr) chicken has 1 recessive allele. Therefore:
[tex]\[ \text{Total recessive alleles} = (25 \times 2) + 30 = 50 + 30 = 80 \][/tex]

Now, calculate the total number of alleles in the population. Each chicken has 2 alleles, so:
[tex]\[ \text{Total alleles} = 100 \times 2 = 200 \][/tex]

The frequency of the recessive allele is then the number of recessive alleles divided by the total number of alleles:
[tex]\[ \text{Frequency of recessive allele} = \frac{\text{Total recessive alleles}}{\text{Total alleles}} = \frac{80}{200} \][/tex]

So the correct expression for the frequency of the recessive allele is:
[tex]\[ \boxed{\frac{80}{200}} \][/tex]

Thus, the correct answer is:
[tex]\[ \boxed{B} \][/tex]

Other Questions