Download Punnett Square Practice Worksheet

Punnett Square Practice
Name: __________________________________
1. Write the phenotype for each of the genotypes.
a) Purple flowers are dominant to white flowers.
PP_____________
Pp____________
pp_______________
b) Hairy knuckles are dominant to non-hairy knuckles in humans.
HH_____________
Hh ___________
hh _________________
c) Round seeds are dominant to wrinkled seeds in pea plants.
RR______________
Rr _____________
rr ____________
2. For each of the following write whether it is homozygous dominant, heterozygous, or homozygous recessive.
a) AA ____________________________
b) Ff ___________________________ c) gg______________________
d) Pp ____________________________
e) tt ___________________________ f) BB _____________________
3. In dogs, dominant allele (F) gives grey fur and the recessive allele (f) gives black fur.
a) The female dog is heterozygous. The male dog is homozygous recessive.
Parent’s Genotypes: _________ x __________
Phenotypes: __________ x ____________
Punnett Square:
b) The female dog has black fur. The male dog has black fur. Figure out the phenotypes and genotypes of their possible
puppies by using a Punnett Square.
Parent’s Genotypes: _________ x __________
Phenotypes: __________ x ____________
Punnett Square:
Offspring’s Genotypes (fraction):
Offspring’s Phenotypes (%):
FF:
Black fur:
Ff:
Grey fur:
ff:
c) The female dog is heterozygous. The male dog is heterozygous. Figure out the phenotypes and genotypes of their
possible puppies by using a Punnett Square.
Parent’s Genotypes: _________ x __________
Phenotypes: __________ x ____________
Punnett Square:
Offspring’s Genotypes (%):
FF:
Ff:
ff:
Offspring’s Phenotypes (fraction):
Black fur:
Grey fur:
4. In dogs, hereditary deafness can be caused by a recessive gene, “d.” A kennel owner has a male dog (Gilbert) that she
wants to use for breeding. The dog can hear.
a) What are the two possible genotypes of Gilbert?
b) The owner can determine his genotype by breeding the dog to a deaf female (dd). Draw two Punnett squares to
illustrate these two possible crosses. If the dog’s genotype is Dd, the owner does not wish to use him for breeding
(why?).
% puppies that can hear:
% puppies that are deaf:
Fraction of puppies that can hear:
Fraction of puppies that are deaf:
Ratio of deaf to hearing:
% puppies that can hear:
% puppies that are deaf:
Fraction of puppies that can hear:
Fraction of puppies that are deaf:
Ratio of deaf to hearing:
c) Draw a Punnett square to show how two hearing dogs could produce deaf offspring.
Having a widow’s peak like Wentworth Miller is dominant.
Not having a widow’s peak, like Rihanna, is recessive.
5) If Wentworth Miller is Aa, and he and Rihanna had children, what are the possible phenotypes and genotypes of
their children? Give the ratio, percent, and fraction.
6) Look at the phenotypes of Beyonce and Jay Z. If these two
had children, could they have children with a widow’s peak? Why or
why not? Use a Punnett Square to explain your answer.