Download Investigating Special Patterns in Heredity

Special Patterns in Genetics:
Incomplete Dominance & Codominance
Name: __________________________________
1. Explain the difference between incomplete dominance and codominance:
2) In some chickens, the gene for feather color is controlled by codominance. The allele for black is
B and the allele for white is b. The heterozygous phenotype is known as erminette.
a. What is the genotype for black chickens?
_______
b. What is the genotype for white chickens?
_______
c. What is the genotype for erminette chickens?
_______
3) What do you think an erminette chicken looks like?
4) If two erminette chickens were crossed, what is the probability that:
a. They would have a black chick?
_____%
b. They would have a white chick?
_____%
c. They would have a erminette chick?
_____%
5) 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? ___________
6) A pink-flowered plant is crossed with a white-flowered plant. What is the probability of producing a pink-flowered
plant?
____%
7) If you were a gardener for a fancy greenhouse and someone wanted to order $5000 worth of pink flowers for a
wedding, what cross would you use? What cross will produce the most pink-flowered plants?
Please show a punnett square to support your answer!
8) In radishes, when a plant homozygous for red radishes is crossed with a plant homozygous for white radishes, plants
bearing purplish-pinkish radishes are produced. What pattern of inheritance does this illustrate?
9) Create a punnett square for a purplish-pinkish radish plant crossed with a white radish plant:
(Create letters to represent these alleles!)
a. What are the phenotypes of the offspring?
10) In some species, dogs can have black gums (B) or pink gums (P) or this trait can show codominance. A lovely spottedgummed Chesapeake Bay retriever just had 8 precious, little pups. Four of the pups have spotted gums like their mother
and 4 have pink gums. What is the likely phenotype of the sneaky neighbor dog?
11) A cross between a black cat & a tan cat produces a tabby pattern (black & tan fur together). What pattern of
inheritance does this illustrate?
12) Norway rats have a lot of variation in the length of their tails because this trait shows incomplete dominance. Some
of these little critters have long tails (L) and some have short tails (S). Show a cross between a homozygous short-tailed
mouse and a heterozygous mouse. Describe what their offspring would look like!
13) The size of kangaroo pouches is determined by the combination of two alleles that an individual receives from its
parents. Pouches can be deep (D) or shallow (d) and the trait is incompletely dominant. Two adult kangaroos have six
babies, three of them have shallow pouches and three of them have pouches of medium depth. What is the genotype &
phenotype of the parent kangaroos?
14) Lacinato kale can have three different types of leaf: extremely curly, flat, or mildly curly. What pattern of inheritance
does this illustrate?
15) The lubber grasshopper is a very large grasshopper, and is black with red & yellow stripes. Assume that the red
stripes are expressed from the homozygous R genotype, yellow stripes from the homozygous r genotype, and both from
the heterozygous genotypes. What pattern of inheritance does this illustrate?
16) What will be the genotype ratio of the F1 generation resulting from a cross of two grasshoppers, both with red &
yellow stripes?
17) What genotypes would be produced by crossing a grasshopper with both color stripes and one with yellow stripes?