Answer :
To solve this problem, we will cross a parent that is homozygous recessive for both traits (bbee) with a dihybrid (BbEe). Here's a step-by-step explanation.
### 1. Identifying Possible Gametes
Parent 1 (bbee): Since this parent is homozygous recessive for both traits, the only possible gamete it can produce is be.
Parent 2 (BbEe): This parent is dihybrid (heterozygous for both traits), so it can produce four types of gametes:
- BE
- Be
- bE
- be
### 2. Constructing the Punnett Square
To construct the Punnett square, list the gametes from Parent 1 on one side (since it only has one type of gamete, it will be along one dimension), and the gametes from Parent 2 along the other side:
[tex]\[ \begin{array}{c|c|c|c|c} & BE & Be & bE & be \\ \hline be & BEbe & Bebe & bEbe & be \\ \end{array} \][/tex]
When we combine these gametes, we get the following offspring combinations:
- BEbe
- Bebe
- bEbe
- bebe
### 3. Determining the Phenotypes
To determine the phenotypes, we look at each allele combination:
1. BEbe:
- B (dominant black fur)
- E (dominant black eyes)
- Phenotype: Black Fur and Black Eyes
2. Bebe:
- B (dominant black fur)
- ee (recessive red eyes)
- Phenotype: Black Fur and Red Eyes
3. bEbe:
- bb (recessive white fur)
- E (dominant black eyes)
- Phenotype: White Fur and Black Eyes
4. bebe:
- bb (recessive white fur)
- ee (recessive red eyes)
- Phenotype: White Fur and Red Eyes
### 4. Counting and Predicting the Fractions
Let's count each phenotype:
- Black Fur and Black Eyes: 1
- Black Fur and Red Eyes: 1
- White Fur and Black Eyes: 1
- White Fur and Red Eyes: 1
Since there are a total of 4 offspring, the predicted fraction for each phenotype will be:
[tex]\[ \begin{array}{|c|c|c|c|c|} \hline & \text{Black Fur and Black Eyes} & \text{Black Fur and Red Eyes} & \text{White Fur and Black Eyes} & \text{White Fur and Red Eyes} \\ \hline \text{Predicted Fraction} & \frac{1}{4} & \frac{1}{4} & \frac{1}{4} & \frac{1}{4} \\ \hline \end{array} \][/tex]
So, the table will look like:
\begin{tabular}{|c|c|c|c|c|}
\hline & \begin{tabular}{c}
Black \\
Fur and \\
Black \\
Eyes
\end{tabular} & \begin{tabular}{c}
Black \\
Fur and \\
Red \\
Eyes
\end{tabular} & \begin{tabular}{c}
White \\
Fur and \\
Black \\
Eyes
\end{tabular} & \begin{tabular}{c}
White \\
Fur and \\
Red \\
Eyes
\end{tabular} \\
\hline \begin{tabular}{c}
Predicted \\
Fraction
\end{tabular} & \frac{1}{4} & \frac{1}{4} & \frac{1}{4} & \frac{1}{4} \\
\hline
\end{tabular}
### 1. Identifying Possible Gametes
Parent 1 (bbee): Since this parent is homozygous recessive for both traits, the only possible gamete it can produce is be.
Parent 2 (BbEe): This parent is dihybrid (heterozygous for both traits), so it can produce four types of gametes:
- BE
- Be
- bE
- be
### 2. Constructing the Punnett Square
To construct the Punnett square, list the gametes from Parent 1 on one side (since it only has one type of gamete, it will be along one dimension), and the gametes from Parent 2 along the other side:
[tex]\[ \begin{array}{c|c|c|c|c} & BE & Be & bE & be \\ \hline be & BEbe & Bebe & bEbe & be \\ \end{array} \][/tex]
When we combine these gametes, we get the following offspring combinations:
- BEbe
- Bebe
- bEbe
- bebe
### 3. Determining the Phenotypes
To determine the phenotypes, we look at each allele combination:
1. BEbe:
- B (dominant black fur)
- E (dominant black eyes)
- Phenotype: Black Fur and Black Eyes
2. Bebe:
- B (dominant black fur)
- ee (recessive red eyes)
- Phenotype: Black Fur and Red Eyes
3. bEbe:
- bb (recessive white fur)
- E (dominant black eyes)
- Phenotype: White Fur and Black Eyes
4. bebe:
- bb (recessive white fur)
- ee (recessive red eyes)
- Phenotype: White Fur and Red Eyes
### 4. Counting and Predicting the Fractions
Let's count each phenotype:
- Black Fur and Black Eyes: 1
- Black Fur and Red Eyes: 1
- White Fur and Black Eyes: 1
- White Fur and Red Eyes: 1
Since there are a total of 4 offspring, the predicted fraction for each phenotype will be:
[tex]\[ \begin{array}{|c|c|c|c|c|} \hline & \text{Black Fur and Black Eyes} & \text{Black Fur and Red Eyes} & \text{White Fur and Black Eyes} & \text{White Fur and Red Eyes} \\ \hline \text{Predicted Fraction} & \frac{1}{4} & \frac{1}{4} & \frac{1}{4} & \frac{1}{4} \\ \hline \end{array} \][/tex]
So, the table will look like:
\begin{tabular}{|c|c|c|c|c|}
\hline & \begin{tabular}{c}
Black \\
Fur and \\
Black \\
Eyes
\end{tabular} & \begin{tabular}{c}
Black \\
Fur and \\
Red \\
Eyes
\end{tabular} & \begin{tabular}{c}
White \\
Fur and \\
Black \\
Eyes
\end{tabular} & \begin{tabular}{c}
White \\
Fur and \\
Red \\
Eyes
\end{tabular} \\
\hline \begin{tabular}{c}
Predicted \\
Fraction
\end{tabular} & \frac{1}{4} & \frac{1}{4} & \frac{1}{4} & \frac{1}{4} \\
\hline
\end{tabular}
