Question

predict the offspring of a dihybrid cross (bbee x bbee)

using the offspring genotype in the punnett square you just completed, determine the phenotype. in other words, what is the predicted fur color and eye color of the offspring? using your punnett square from the left, determine the predicted fraction for each phenotype in the data table below.

	black fur and black eyes	black fur and red eyes	white fur and black eyes	white fur and red eyes

Explanation:

Analyze the Punnett square genotypes

Using the Punnett Square and Dihybrid Cross knowledge points
The completed Punnett square for the cross \(BbEe \times BbEe\) contains the following 16 genotypes:

• Row 1: \(BBEE\), \(BBEe\), \(BbEE\), \(BbEe\)
• Row 2: \(BBEe\), \(BBee\), \(BbEe\), \(Bbee\)
• Row 3: \(BbEE\), \(BbEe\), \(bbEE\), \(bbEe\)
• Row 4: \(BbEe\), \(Bbee\), \(bbEe\), \(bbee\)

Determine phenotype rules

Using the Dihybrid Cross knowledge point

• Black Fur: presence of at least one dominant allele \(B\) (\(B_-\))
• White Fur: homozygous recessive alleles \(bb\)
• Black Eyes: presence of at least one dominant allele \(E\) (\(E_-\))
• Red Eyes: homozygous recessive alleles \(ee\)

Count phenotypes in the grid

Using the Phenotypic Ratio knowledge point

• Black Fur and Black Eyes (\(B_-E_-\)):

\(BBEE\) (1), \(BBEe\) (2), \(BbEE\) (2), \(BbEe\) (4) \(
ightarrow 1 + 2 + 2 + 4 = 9\)

• Black Fur and Red Eyes (\(B_-ee\)):

\(BBee\) (1), \(Bbee\) (2) \(
ightarrow 1 + 2 = 3\)

• White Fur and Black Eyes (\(bbE_-\)):

\(bbEE\) (1), \(bbEe\) (2) \(
ightarrow 1 + 2 = 3\)

• White Fur and Red Eyes (\(bbee\)):

\(bbee\) (1) \(
ightarrow 1\)

Answer:

Using your Punnett square from the completed dihybrid cross, the predicted fraction for each phenotype in the data table is:

• Black Fur and Black Eyes: <blank>9</blank>/16
• Black Fur and Red Eyes: <blank>3</blank>/16
• White Fur and Black Eyes: <blank>3</blank>/16
• White Fur and Red Eyes: <blank>1</blank>/16