# How to Solve Dihybrid Punnett Squares by K0x8Dfd

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```									           How to Solve Dihybrid Punnett Squares
FIVE steps to solving a DIHYBRID Punnett square word problem.
a.) Assign letters to the different alleles for the trait. (2 points)
b.) Write the cross that you will be making. (2 points)
c.) Use the FOIL method to determine the combination of alleles for each gamete. (2 points)
d.) Set up the Punnett Square by separating your female and male gametes. Solve. (2 points)
e.) Answer the question and circle or square off the answer. (2 points)

Problem:

In fruit flies, red eyes are dominant sepia eyes,
normal wings are dominant to wingless, and gray
bodies are dominant to ebony bodies. Cross a male
that is homozygous dominant for both eye color and
wing type with a female that is homozygous
recessive for both eye color and wing type. What
would be the proportions of phenotypes in the F1 generation?

Step 1: Assign letters to the different alleles for the trait.

Step 2: Write the cross that you will be making:                 ________________ X _________________

Step 3: Use the FOIL method to determine the combination of alleles for each gamete.

Step 4: Set up the Punnett Square by separating your female and male gametes. Solve. (

________________          ________________      ________________   ________________

______________

______________

______________

______________

Step 5: Answer the question and circle or square off the answer.
What would be the proportions of phenotypes in the F1 generation?
Independent Practice
Problem:

In certain bacteria, an oval shape is dominant over round
and thick cell walls are dominant over thin. Cross a
heterozygous oval, thick cell walled bacteria with a round,
thin cell walled bacteria. What are the phenotypic and
genotypic ratios of the offspring?

Step 1: Assign letters to the different alleles for the trait.

Step 2: Write the cross that you will be making:                 ________________ X _________________

Step 3: Use the FOIL method to determine the combination of alleles for each gamete.

Step 4: Set up the Punnett Square by separating your female and male gametes. Solve. (

________________          ________________     ________________   ________________

______________

______________

______________

______________

Step 5: Answer the question and circle or square off the answer.
What are the phenotypic and genotypic ratios of the offspring?

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