Name______Date ______

Codominance problems:

Problems involving codominance have the heterozygous (hybrid) individual’s phenotype being a combination of both dominant alleles and are completely expressed. (Black and white results in black and white, not grey)

In camillia flowers, the allele for the red flowers is codominant to the allele for the white flowers. A cross between the two will result in both red and white on each pedal.

Use _____ for the red camellia allele

_____ for the white camellia allele

What is the phenotype of each of the following (you will need two alleles for each phenotype)

______= Red _____ = Red & White ______= White

  1. Cross a red camellia with a hybridcamellia. _____ X ______

What percent of the offspring could be RED _____, RED & WHITE _____, or WHITE ______?

  1. Cross two hybridcamellias with each other. _____ X ______

What percent of the offspring could be RED _____, RED & WHITE _____, or WHITE ______?

  1. Cross a hybrid and a white camellia. ______X ______

What percent of the offspring could be RED _____, RED & WHITE _____, or WHITE ______?

In humans, there are four different types of blood alleles, the A, B and o alleles. The A and B alleles are codominant to eachother so with hybrids, the blood type is AB. Both the A and the B antigen alleles are both dominant to the o allele. Remember it this way, A = B > o.

Use ____ for the A antigen allele

____ for the B antigen allele

____ for the o antigen allele

What are the genotype possibilities of each of the following blood types?

Blood type Genotype

A_____ or _____

B_____ or _____

AB_____

O_____

  1. Cross a person who has AB blood with another with O type blood. ______X ______

What percent of the offspring could be: A ______, B ______, AB ______or O ______?

  1. Cross a hybrid A person with a hybrid B person. ______X ______

What percent of the offspring could be: A ______, B ______, AB ______or O ______?

  1. Cross two people with O type blood. ______X ______

What percent of the offspring could be: A ______, B ______, AB ______or O ______?

  1. A woman has A blood and her child has O type blood. There are two men that could be the father of the child. Potential dad #1 has AB blood and Potential dad #2 has B type blood.

Mom’s Genotype: In order for her to have an O type child, what is her genotype? ______

Dad #1’s Genotype _____

Dad #2’s Genotype ______or ______

Dad #1: _____X_____Dad #2: ______X ______

Which of the two fathers could not possibly be the father of the O type child? ______

In humans, the gene to produce normal shaped red blood cells is codominant with the mutated gene to produce sickled red blood cells. People who inherit both genes have both normal shaped red blood cells and sickled shaped red blood cells and show some of the traits for being a person with sickle cell anemia (SCA).

Use ____ for the Normal shaped red blood cell allele

____ for the Sickle shaped red blood cell allele

  1. Cross a person who has all normal red blood cells with a person who is a carrier (hybrid) for SCA.

______X _____

What is the probability of having children who are: Normal _____, Carriers ______, or have SCA_____?

  1. Cross two carriers. _____ X _____