PUNNETT SQUARE PRACTICE PROBLEMS
Don’t forget to switch turns with who is the teacher and who is the student...
Example: There are two parents. The father contains a dominant allele for brown hair (H) and a recessive allele for
blonde hair (h). The mother contains both dominant alleles for brown hair (H). Make a punnett square and table to
show the probability of their child having either brown/blonde hair.
H
h
H
H
HH
Hh
hh
HH
Hh
HH
Hh
2/4 or 1/2
2/4 or 1/2
0/4
50%
50%
0%
Phenotype for offspring: There is a 100% that the offspring will have brown hair, because the dominant gene will
overpower the recessive gene.
1. There are two parents. The father contains two recessive alleles for blue eyes (e). The mother contains one
dominant allele for brown eyes (E) and one recessive allele for blue eyes (e). Create a punnett square to show the
possible outcomes for their offspring. Include a percent/fraction/phenotype table.
2. Black fur (B) in guinea pigs is dominant over white fur (b). Find the probability of a black offspring in a cross: bb
x bb. Create a punnett square to show the possible outcomes for their offspring. Include a
percent/fraction/phenotype table.
3. Black fur (B) in guinea pigs is dominant over white fur (b). Find the probability of a black and white offspring in
a cross: BB x Bb. Create a punnett square to show the possible outcomes for their offspring. Include a
percent/fraction/phenotype table.
4. Black fur (B) in guinea pigs is dominant over white fur (b). Find the probability of a homozygous offspring in a
cross: BB x BB. Create a punnett square to show the possible outcomes for their offspring. Include a
percent/fraction/phenotype table.
5. SpongeBob Square pants recently met SpongeSusie Round pants at a dance. SpongeBob Square pants is
heterozygous (Ss) for his square shape, whereas SpongeSusie is homozygous (cc) for her circle shape. Please create
a punnett square showing the possible outcomes for their offspring. Include a percent/fraction/phenotype table.
6. Patrick met Patti while eating a crabby patty. Both of them are heterozygous (Pp) for their pink color, which is
dominant over a yellow body color. Create a punnett square to show the possible outcomes for their offspring.
Include a percent/fraction/phenotype table.
7. M is dominant for no magical abilities. m is recessive for possessing magical abilities. If Harry Potter (mm)
married Ginny Weasley (mm), will their children have magical abilities? Please create a punnett square showing
the possible outcomes for their offspring. Include a percent/fraction/phenotype table.
8. Harry Potter, who has brown hair, marries Ginny, who has red hair. Both Harry and Giney are homozygous.
Brown hair (H) is dominant and red hair (h) is recessive. Create a punnett square to show the possible outcomes for
their offspring. Include a percent/fraction/phenotype table.
9. Squidward, who is heterozygous for light blue body color (dominant) married a girl who was also heterozygous
for a light blue body. (NOTE: light green body is recessive). Please create a punnett square to show the possible
outcomes for their offspring. Include a percent/fraction/phenotype table. (HINT: Use “B” to represent blue, or
dominant, and use “g” to represent green or recessive)
10. CREATE YOUR OWN! You and your partner will create your own punnett square practice problem. Once you
write it down on a sheet of paper, have your partner try to solve your question by completing a punnett square and
percent/fraction/phenotype table.
**Always remember to include the PHENOTYPE**