Name:______
Class Period:______
Incomplete & Codominance Problems
1. In radishes, the shape may be long or round or oval. Crosses between long and round produce oval. Diagram a cross between a long and a round radish. Why is it not necessary to say homozygous or heterozygous?
LL = long
RR = round
____ = oval
2. Yellow guinea pigs crossed with white ones always produce cream-colored offspring. What genotypes and phenotypes are produced when two cream-colored guinea pigs are crossed? Show the cross and summarize.
3. Four O’clocks may have either white, red, or pink petals. What kind of dominance is this? ______Show the following crosses and summarize each.
a. white x red c. white x pink
b. pink x pink d. red x pink
4. In shorthorn cattle, the gene for red coat color (R) is not dominant over the gene for white coat color (W). The heterozygous combination (RW) produces an intermediate color known as a roan. Diagram a cross between a homozygous bull with red fur and a homozygous cow with white fur. Carry this cross to the F2 generation. Summarize both.
5. A man with type O blood marries a woman with type AB blood.
a. What is the genotype of the man? ______
b. What is the genotype of the woman? ______
c. What are the possible phenotypes of their children?
______
d. What are the possible genotypes of their children?
______
e. Genotype ratio: ______
f. Phenotype ratio: ______
g. Suppose that one of the children needs an operation and has
type B blood. Can a transfusion be safely given to the child
from either parent? ______Explain. ______
6. Vincent has type A blood and his mother has type O blood.
Christine has type B blood and her father has type O blood.
a. What is Vincent’s genotype? ______
b. What is Christine’s genotype? ______
c. What genotypes might Christine’s mother have?
______
d. Suppose Christine and Vincent get married. What is the
probable genotypes and ratio of their offspring?
______
e. What is the probable phenotypes and ratio of their children?
______
7. Normal hemoglobin can be represented by the gene HA. The
gene for sickle cell hemoglobin is HS.
a. What type of gene interaction is involved in sickle cell anemia?
Incomplete or Codominance
b. Two people who have the genotype HAHS marry. What
percentage of their children are likely to be sickle cell
sufferers? ______
c. What percentage of their children are likely to be resistant
to malaria and suffer few effects of the sickle cell disease
because they only carry the gene?
______
8. Henry the Eighth decides that he will get rid of his first wife, Catherine. He claims that their child, Mary, is really the child of his brother to whom Catherine had been married for a short time before he died. Henry has type AB blood, Catherine has type B blood, and Mary has type A blood. Henry’s brother had type O blood. Can Henry’s brother be Mary’s father?______Explain.
Give the genotypes, as far as possible, of the following:
Henry ______
Catherine ______
Mary ______
Henry’s brother ______
What are the possible blood types (phenotypes) of Henry’s parents?
______and ______
9. A dagger with type A blood was found beside a murdered man. The victim, Shady Sam, had type O blood. His wife, Sparing Sara, had type A blood. Her daughter, Wee-Susan, had type O blood and was known to dislike her father. Shady Sam’s business partner, Nimble Fingers, was in love with Sparing Sara. His blood type was not discovered, but his son, Simple, who was angry with Nimble Fingers for being disloyal to his mother, knew that his mother’s blood type was type AB. The only other clue found was that Simple’s blood type was different from his mother’s. Who could have committed the murder? ______
Give the genotypes, as far as possible, of all concerned.
Shady Sam ______Mrs. Nimble Fingers ______
Sparing Sara ______Nimble Fingers ______
Wee-Susan ______Simple ______
Dagger ______