Name:___________________________________________  Date: _________________

 

Practice with Punnett Squares

 

1.      In chickens, brown feather are dominant to yellow feathers.

a.       Which trait is the dominant trait?

 

 

b.      Which trait is the recessive trait?

 

 

c.       What letter of the alphabet should you use? (Hint: first letter of the dominant trait)

 

d.      What would be the genotype of a homozygous brown chicken?

 

e.       What would be the genotype of a yellow chicken?

 

f.       Cross a homozygous brown chicken with a yellow chicken:

 

_______________________  X ______________________

 

 

 

 

 

 

 

 

 

 

 

 

 

 

g.      What is the resulting phenotypic ratio?

 

 

h.      What is the resulting genotypic ratio?

 

 

2.      In humans, having a widow’s peak is dominant to a normal hairline.

a.       Which trait is the dominant trait?

 

b.      Which trait is the recessive trait?

 

c.       What letter of the alphabet should you use? (Hint: first letter of the dominant trait)

 

 

d.      What would be the genotype of a heterozygous human?

 

e.       Does a heterozygous human have a widow’s peak or not?

 

 

f.       Cross a heterozygous human with a another heterozygous human:

 

_______________________  X ______________________

 

 

 

 

 

 

 

 

 

 

 

 

 

 

g.      What is the resulting phenotypic ratio?

 

 

h.      What is the resulting genotypic ratio?

 

 

3.      In cows, having horns is dominant to being polled (no horns).

 

a.       Cross a heterozygous cow with a polled cow:

 

_______________________  X ______________________

 

 

 

 

 

 

 

 

 

 

 

 

 

 

b.      What is the resulting phenotypic ratio?

 

 

c.       What is the resulting genotypic ratio?