Genetic Crosses with 2 Traits

worksheetBeginning biology students can really struggle with dihybrid crosses and setting up Punnet squares that have two traits.   Most introductory biology texts suggest using the 4×4 square and the “FOIL” method of determining the gametes that are placed at the sides of the square.

FOIL = first, outer, inner, last

genetics foil

This worksheet starts with squares that are already set up, and then progresses to where students must set the squares up on their own.  Many students will also realize that they do not need to fill out entire squares if the rows or columns contain repeated letter combinations.

Time Required:  15-25 minutes
Grade Level:  9-12

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