Name: ________________________________
Genetics Practice Problems – Complete, Incomplete and Codominance Problems
1.
2.
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4.
5.
In guinea pigs, white fur is recessive and black fur is dominant.
a.
Write a key for these alleles.
b.
What will the offspring be from a cross between a white guinea pig and a heterozygous guinea pig?
c.
What would the phenotypic and genotypic ratios be for this cross?
When red cattle are bred with white cattle they produce roan (red and white hairs) 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?
In the petunia flower, a pure breeding red flower is crossed with a white one to produce all pink offspring.
a.
What form of inheritance is this?
b.
Show the genotypes of the parents and the F1 offspring of a cross between a red and white petunia.
c.
What would the expected offspring if the F 1 plant from above were test crossed to the red parent?
Free ear lobes are dominant over attached ear lobes.
a.
What will the F1 offspring be from a cross between two heterozygous free ear lobed parents?
b.
What are the phenotypic and genotypic ratios?
In dogs, gum coloration is codominant. The dog’s gums can be pink, black, and pink with black spots.
a.
You have a spotted gummed Labrador retriever who just had 8 pups. 4 of the pups have spotted gums like your
dog, and the other 4 have pink gums.
b.
What is the likely phenotype of the sneaky neighbor dog?
6.
7.
8.
9.
In aliens, hairy tongues are recessive to normal hairless tongues.
a.
If a male who is heterozygous normal tongued has children with a homozygous normal tongued female, what
would the genotypes and phenotypes of their offspring be?
b.
What percentage would be hairy tongued?
c.
What percentage would be normal tongued?
In snapdragons, flower color is controlled by incomplete dominance. The two alleles are for red and white. The
heterozygous genotype has a pink phenotype.
a.
If I cross two heterozygous snapdragons, what are the possible outcomes of the offspring, using percentages?
b.
If I have a white snapdragon, but want to make red offspring, what should I do?
c.
What if I still have the white snapdragon, but want to make sure that I only make more white offspring, what
should I do?
d.
What cross between two different snapdragons will produce the most pink-flowered plants? Show a Punnett
square to support your answer.
In smiley faces, eye shape can be starred, circular or a circle with a star in it.
a.
If I cross a star eyed smiley face with a circle eyed smiley face, what are the phenotypes of the offspring?
b.
What are their genotypes?
A Hoo (from Hoo-ville) can have curly hair, spiked hair, or a mix of both curly and spiked hair.
a.
What pattern of inheritance is this?
b.
If I cross a spiked hair hoo with a curl hair hoo, what can I expect from my offspring?
10. Two short-tailed cats are bred together. They produce three kittens with long tails, five with short tails, and two without any
tails.
a.
From these results, how do you think tail length in these cats are inherited?
b.
Show the genotypes for both the parents and the offspring to support your answer.