Question 17 of 26

The gene for fur color in a rabbit population has three alleles: an allele for white fur [tex]\([W_1]\)[/tex], an allele for brown fur [tex]\([B_1]\)[/tex], and an allele for black fur [tex]\([B_2]\)[/tex].

The table represents the gene pool for this population.

[tex]\[
\begin{tabular}{|c|c|c|}
\hline
$W_1$ & $B_2$ & $B_1$ \\
\hline
$B_1$ & $W_1$ & $B_2$ \\
\hline
$B_1$ & $W_1$ & $B_2$ \\
\hline
$B_2$ & $B_1$ & $B_2$ \\
\hline
$W_1$ & $B_2$ & $W_1$ \\
\hline
$W_1$ & $B_2$ & $B_1$ \\
\hline
\end{tabular}
\][/tex]

What is the frequency of the allele that codes for brown fur?

A. [tex]\(\frac{13}{18}\)[/tex]

B. [tex]\(\frac{5}{5}\)[/tex]

C. [tex]\(\frac{5}{13}\)[/tex]

D. [tex]\(\frac{5}{18}\)[/tex]



Answer :

To determine the frequency of the allele that codes for brown fur [tex]\((B_1)\)[/tex], follow these steps:

1. List All Alleles:
Extract all the alleles from the given table.

The table is:
```
W1 B2 B1
B1 W1 B2
B1 W1 B2
B2 B1 B2
W1 B2 W1
W1 B2 B1
```

Combine all the alleles into a single list:
```
W1, B2, B1, B1, W1, B2, B1, W1, B2, B2, B1, B2, W1, B2, W1, W1, B2, B1
```

2. Count the Total Number of Alleles:
Count the number of elements in the list. There are 18 alleles in total.

3. Count the Occurrences of the Brown Fur Allele [tex]\(B_1\)[/tex]:
Identify how many times [tex]\(B_1\)[/tex] appears in the list. The allele [tex]\(B_1\)[/tex] appears 5 times.

4. Calculate the Frequency of [tex]\(B_1\)[/tex]:
The frequency of an allele is given by the number of occurrences of that allele divided by the total number of alleles. So, the frequency of [tex]\(B_1\)[/tex] is:
[tex]\[ \text{Frequency of } B_1 = \frac{\text{Number of } B_1 \text{ alleles}}{\text{Total number of alleles}} = \frac{5}{18} \][/tex]

5. Match to the Given Choices:
Compare the computed frequency with the provided options:

- [tex]\(A. \frac{13}{18}\)[/tex]
- [tex]\(B. \frac{5}{5}\)[/tex]
- [tex]\(C. \frac{5}{13}\)[/tex]
- [tex]\(D. \frac{5}{18}\)[/tex]

The correct choice is:
```
D. [tex]\(\frac{5}{18}\)[/tex]
```

Therefore, the frequency of the allele that codes for brown fur [tex]\((B_1)\)[/tex] in this population is [tex]\( \frac{5}{18} \)[/tex], which corresponds to option D.