Name:
Period:
Date:
Part I: Incomplete Dominance Problems
1. In snapdragons, flower color is controlled by incomplete dominance. The two alleles are red (R) and white (r). The
heterozygous genotype is expressed as pink.
a. What is the phenotype of a plant with the genotype RR? ___________
b. What is the phenotype of a plant with the genotype rr? ___________
c. What is the phenotype of a plant with the genotype Rr? ___________
2. A pink-flowered plant is crossed with a white-flowered plant. What is the probability of producing a pink-flowered
plant? ____%
Parents: ____ X ____
3. What cross will produce the most pink-flowered plants? Show a punnett square to support your answer.
Parents: ____ X ____
4. In Andalusian fowls, black individuals (B) and white individuals (W) are homozygous.
A homozygous black bird is crossed with a homozygous white bird. The offspring are all bluish-gray. Show the cross as
well as the genotypes and phenotypes of the parents and offspring.
5. What results if a black individual is crossed with a bluish-gray individual? (SHOW YOUR WORK)
13. If two bluish-gray individuals were crossed, what would be the ratios for both phenotype and genotype of the
offspring?
Part 2: Mystery Bull - Codominance
Howdy! My name is Bob Howard, and I own 20 purebred (RR) cows. Something strange happened several months ago.
During a violent storm, all of the fences that separate my cattle from my neighbor’s cattle blew down. During the time
that the fences were down, three bulls, one from each of my neighbors, had access to my cows. For a while, I thought
that none of the bulls found my cows, but over the months, I have come to the conclusion that all of my cows are
expecting calves. One of the bulls is the father. Which bull is it? (Roan bull = RW; Red bull = RR; White bull = WW)
Using your punnet squares, you can decipher the information and find out who is the father of Bob’s new calves.
Complete the questions below using your information from above.
Purebred Red Cow – genotype:
Purebred White Cow – genotype:
Roan Cow – genotype:_____
Ratio of Bob’s Calves (from paragraph above)
Phenotypic Ratio:
Red :
Roan :
White
Genotypic Ratio:
Red :
Roan :
White
Fill in the information for the offspring of:
Ferdinand + Bob’s Cows:
Rocky + Bob’ Cows:
Phenotypic Ratio:
Red :
Roan :
White
Phenotypic Ratio:
Red :
Roan :
White
Genotypic Ratio:
Red :
Roan : _
White
Genotypic Ratio:
Red :
Roan : _
White
Rufus + Bob’s Cows:
Phenotypic Ratio:
Red :
Roan :
White
Genotypic Ratio:
Red :
Roan : _
White
Which bull is the father of Bob’s new calves?