Name:____________________________
Punnet Square Practice
Date:_____________________________
Assignment #:_________Block:________
Directions: Answer the following questions as indicated. Remember
CAPITAL letters stands for dominant and LOWER CASE letters stand for recessive.
1. Widow’s peak (W) is dominant over a straight hairline (w). What letters would represent the genes
for a:
A. Pure dominant parent? _________________
B. Hybrid dominant parent? _______________
C. Pure recessive parent? _________________
2. Using widow’s peak as the trait, which trait (widow’s peak or straight hairline) would each of these
parents show?
A. WW __________________________________
B. ww ___________________________________
C. Ww __________________________________
3. For the following crosses, use the information given above in #1, to complete the punnet square and
provide the probabilities for each cross, in %:
A. Show the cross between two pure dominant parents.
Genotype:
Phenotype:
Window’s peak ______%
Genotype:
Pure dominant ______%
Hybrid ______%
Genotype:
Straight hairline ______%
Pure recessive ______%
B. Show the cross between two pure recessive parents.
Genotype:
Phenotype:
Window’s peak ______%
Straight hairline ______%
Pure dominant ______%
Hybrid ______%
Pure recessive ______%
Genotype:
Genotype:
C. Show the cross between a pure dominant parent and a pure recessive parent.
Phenotype:
Genotype:
Window’s peak ______%
Straight hairline ______%
Genotype:
Genotype:
Pure dominant ______%
Hybrid ______%
Pure recessive ______%
D. Show the cross between a pure dominant parent and a hybrid parent.
Genotype:
Phenotype:
Window’s peak ______%
Straight hairline ______%
Genotype:
Genotype:
Pure dominant ______%
Hybrid ______%
Pure recessive ______%
E. Show the cross between a hybrid parent and a pure recessive parent.
Phenotype:
Genotype:
Window’s peak ______%
Straight hairline ______%
Pure dominant ______%
Hybrid ______%
Pure recessive ______%
Genotype:
Genotype: