Punnett Square Practice 2
Complete the following monohybrid crosses: draw a Punnett square, list the ratio and describe the offspring. Be sure
to remember that the capital letter represents the dominant allele.
Example
A green pea plant (GG) is being crossed with a green pea plant (Gg).
G
g
G
G
GG
GG
Gg
Gg
Genotype Probabilities: 50% GG and 50% Gg
Phenotype Probabilities: 100% green pea plants
1) A green pea plant (Gg) is crossed with a yellow pea plant (gg).
Genotype Probabilities:
Phenotype Probabilities:
2) A tall plant (TT) is crossed with a tall plant (Tt).
Genotype Probabilities:
Phenotype Probabilities:
3) A tall plant (Tt) is crossed with a short plant (tt).
Genotype Probabilities:
Phenotype Probabilities:
4) A white flower (rr) is crossed with a white flower (rr).
Genotype Probabilities:
Phenotype Probabilities:
Punnett Squares Part 2
Complete the Punnett Squares for each of the described situations and then use the probability data to answer the
questions. In each situation, black fur is dominant to brown fur in rabbits.
1.
A homozygous dominant black furred rabbit is crossed with a heterozygous black furred rabbit.
Why can’t any of the offspring have brown fur?
2.
Two heterozygous rabbits are crossed.
If 12 bunnies are born as a result of the following cross, how many
would you expect to have brown fur? Show your work.
3.
A heterozygous rabbit is crossed with a brown furred rabbit.
If you were looking to sell brown bunnies, would you want to
breed the parents from problem 2 or problem 3? Support your
answer with mathematical evidence.
4.
A heterozygous rabbit is crossed with a brown furred rabbit and 10 bunnies are born. Eight bunnies have
black fur and 2 bunnies have brown fur. Does this match the expected probability data for such a cross?
Provide mathematical evidence to support your claim.
5.
How is it possible for that cross in question 4 to actually produce 8 black fur bunnies and 2 brown fur
bunnies?