Download Name____________________ ___________________ Per___

Name___________________________________________________________________ Per____________ Due _______________
Dihybrid, Incomplete Dominance, and Co-Dominance Practice Problems
1. In Kingwood Texas, there is a creature known as a panther. It comes in three colors, yellow, green, and blue. This trait is controlled
by a single gene with incomplete dominance. A homozygous (YY) individual is yellow, a homozygous (Y’Y’) individual is blue, and a
heterozygous (YY’) individual is forest green. What would be the genotypic and phenotypic ratios of the offspring if a yellow panther
were crossed with a blue one?
Key: ___________________________________________________
Cross: _________________________________________________
Phenotypic Ratio: _________________________________________
Genotypic Ratio: __________________________________________
What type of inheritance is this? _______________________________
2. Wolves are sometimes observed to have black coats and blue eyes. Assume that these traits are controlled by single genes that are
located on two different chromosomes. Assume further that normal coat color is dominant to black coat color and that brown eyes
are dominant to blue eyes. Suppose a male wolf with a black coat and blue eyes mates with a female wolf heterozygous for both
normal coat color and brown eyes. What would the resulting pack look like?
Key: ________________________________________________________________________________________________
Cross: _______________________________________________________________________________________________
Gametes: _____________________________________________________________________________________________
Phenotypic Ratio: _________________________________________________________________________________________
Genotypic Ratio: __________________________________________________________________________________________
3. There is a certain breed of cattle that has a red coat, and when bred with cattle with a white coat, they produce roan (red
and white haired) offspring.
a. What type of inheritance is this? __________________________________________
b. If two roan cattle are crossed, what is the probability of red, white, and roan colors in their offspring?
Key: _______________________________________________________
Cross: ______________________________________________________
Phenotypic Ratio: _____________________________________________
Genotypic Ratio: ______________________________________________
4. In Smileys, eye shape can be starred, circular, or a circle with a star. What type of inheritance is this? ______________________
Write the genotypes of the smileys below each picture.
Key: _________________________________________________________________
Genotype:
___________
_________
___________
a. Cross a star-eyed smiley and a circle eyed smiley and show their expected phenotypic and genotypic ratios.
Cross: __________________________________________
Phenotypic Ratio: ______________________________________
Genotypic Ratio: _______________________________________
b. Cross a circle-star eyed smiley with a circle eyed smiley.
Cross: __________________________________________
Phenotypic Ratio: ______________________________________
Genotypic Ratio: _______________________________________
5. In snapdragons, flower color is controlled by incomplete dominance. The two alleles are for red and white. The
heterozygous genotype has a pink phenotype.
Key: __________________________________________________________________
a. If I cross two heterozygous snapdragons, what are the possible outcomes of the offspring?
Cross: __________________________________________
Phenotype Ratio: ___________________________________
b. If I have pink snapdragons, but want to make red offspring, what should I do?
c. What cross will produce the most pink-flowered plants? Show a Punnett square to support your answer!