Codominance PRACTICE
1. A black (FB FB) feather chicken is crossed with a white (FW FW) feathered chicken.
a.
b.
Identify the phenotype ratio of the offspring.
Identify the genotype ratio of the
offspring.
2. A black (FB FB) feathered chicken is crossed with a black and white (FB FW) feathered
chicken.
a.
Identify the phenotype ratio of the offspring.
b.
Identify the genotype ratio of the offspring.
3. A black and white (FB FW) feathered chicken is crossed with a white (FW FW) chicken.
a.
Identify the phenotype ratio of the offspring.
b.
Identify the genotype ratio of the offspring.
4. A black and white (FB FW) feathered chicken is crossed with a black and white (FB FW)
feathered chicken.
a.
Identify the phenotype ratio of the offspring.
b.
Identify the genotype ratio of the offspring.
Questions:
1. Is it possible for two black chickens to produce anything other than black chickens? Why
(not)?
2. Is it possible for two white chickens to produce anything other than white chickens?
Why (not)?
3. Is it possible for two black and white chickens to produce anything other than black and
white chickens? Why (not)?
4. What phenotype does each “parent” need to be to produce only black and white offspring
chickens? Why?
5. Why do we refer to this as codominance?
Incomplete Dominance PRACTICE
1. A red (CR CR) carnation is crossed with a white (Cw Cw) carnation.
a. Identify the phenotype ratio of the
offspring.
b.
Identify the genotype ratio of the offspring.
2. A red (CR CR) carnation is crossed with a pink (CR Cw) carnation.
a. Identify the phenotype ratio of the
offspring.
b.
Identify the genotype ratio of the offspring.
3. A pink (CR Cw) carnation is crossed with a white (Cw Cw) carnation.
a. Identify the phenotype ratio of the
offspring.
b.
Identify the genotype ratio of the offspring.
4. A pink (CR Cw) carnation is crossed with a pink (CR Cw) carnation.
c. Identify the phenotype ratio of the
offspring.
d.
Identify the genotype ratio of the offspring.
Questions:
1. Is it possible for two red carnations to produce anything other than red carnations? Why
(not)?
2. Is it possible for two white carnations to produce anything other than white carnations?
Why (not)?
3. Is it possible for two pink carnations to produce anything other than pink carnations? Why
(not)?
4. What phenotype does each “parent” need to be to produce only pink offspring carnations?
Why?
5. Why do we refer to this as incomplete dominance?
Multiple Genes (Ex: Blood Types) PRACTICE
1. A man with type AB blood and a woman with type O blood have a child.
a. What are the child’s probabilities for each
blood type?
b.
2.
What are the child’s probabilities for each
genotype?
A man with type A blood (genotype AA) and
a woman with type O blood have a child.
a. What are the child’s probabilities for each
blood type?
b.
What are the child’s probabilities for each
genotype?
3. A man with type B blood (genotype BO) and a woman with type O blood have a child.
a. What are the child’s probabilities for each
blood type?
b.
What are the child’s probabilities for each
genotype?
4. A man with type AB blood and a woman with type AB blood have a child.
a. What are the child’s probabilities for each
blood type?
b.
What are the child’s probabilities for each
genotype?
Questions:
1. A man with type A blood and a woman with type B blood have a child. Is it possible for
that child to have type O blood? Why (not)?
2. A man with type AB blood and a woman with an unknown blood type have a child. Is it
possible for that child to have type O blood? Why(not)?
3. Why is type O blood considered the “universal donor”?
4. Why is type AB blood considered the “universal acceptor”?
5. Do you know your blood type? If so, what is it? If you’re type O, please consider giving
blood. Even if you’re not type O, please consider giving blood.