Name: ______Date: ______Seat# ______Period: ____
Practice Problems: Beyond Dominant and Recessive Alleles
Incomplete Dominance
1. A cross between a black bird and a white bird produces gray offspring.
Black = (CB); white = (CW)
A. What are the genotypes of the parents? ______
B. What are the genotypes of the offspring? ______
C. Cross 2 gray birds and give the phenotypes of the offspring.
Genotypes ______Ratio ______
Phenotypes ______Ratio ______
2. In mice, the allele for brown hair is incompletely dominant over white hair.
Brown = (CR) white = (CW)
A. Cross a white mouse with a brown mouse (F1 generation).
B. Cross the F1 generation to get the F2 generation
II. CoDominance
Name: ______Date: ______Seat# ______Period: ____
Practice Problems: Beyond Dominant and Recessive Alleles
Incomplete Dominance
1. A cross between a black bird and a white bird produces gray offspring.
Black = (CB); white = (CW)
A. What are the genotypes of the parents? ______
B. What are the genotypes of the offspring? ______
C. Cross 2 gray birds and give the phenotypes of the offspring.
Genotypes ______Ratio ______
Phenotypes ______Ratio ______
2. In mice, the allele for brown hair is incompletely dominant over white hair.
Brown = (CR) white = (CW)
A. Cross a white mouse with a brown mouse (F1 generation).
B. Cross the F1 generation to get the F2 generation
II. CoDominance
Codominance
3. In cattle, the alleles for red coat (CR) and white coat (CW) behave as the co-dominants. Both red and white hairs are produced in the heterozygote producing a coat pattern that is called "roan."
A. Give the phenotypic and genotypic ratios to be expected among the offspring from a cross of two roan animals.
Genotypes ______Ratio ______
Phenotypes ______Ratio ______
B. What are the expected genotypic and phenotypic ratios from a cross of a roan animal and a white one?
Genotypes ______Ratio ______
Phenotypes ______Ratio ______
4. A cross between a black cat (CB) and a tan cat (CT) produces a tabby pattern (black and tan fur together).
A. Why does this illustrate codominance?
B. Write the alleles you would use for each phenotype.
C. Cross a tabby with a black cat.
D. What percentage of the offspring are tabby cats? ______
Codominance
3. In cattle, the alleles for red coat (CR) and white coat (CW) behave as the co-dominants. Both red and white hairs are produced in the heterozygote producing a coat pattern that is called "roan."
A. Give the phenotypic and genotypic ratios to be expected among the offspring from a cross of two roan animals.
Genotypes ______Ratio ______
Phenotypes ______Ratio ______
B. What are the expected genotypic and phenotypic ratios from a cross of a roan animal and a white one?
Genotypes ______Ratio ______
Phenotypes ______Ratio ______
4. A cross between a black cat (CB) and a tan cat (CT) produces a tabby pattern (black and tan fur together).
A. Why does this illustrate codominance?
B. Write the alleles you would use for each phenotype.
C. Cross a tabby with a black cat.
D. What percentage of the offspring are tabby cats? ______