Download Incomplete Dominance and Multiple Alleles Review

Name____________________________________Date________________Period____
Review on Incomplete Dominance/ Codominance
and Multiple Alleles
1. In snapdragon flowers, the red (CR) and white (CW) flower color alleles
exhibit incomplete dominance. Flowers with the genotype CRCW are pink.
Fill in the Punnett square below to determine the probabilities of different
offspring in a cross of two pink snapdragon flowers (CRCW x CRCW).
Pollen
Egg
Offspring Phenotypes:
__________________________________________
Phenotype Ratio:
__________________________________________
Probability of red flowered offspring ____________
Probability of pink flowered offspring ___________
Probability of white flowered offspring __________
2. Circle all the traits below that exhibit incomplete dominance or
codominance.
3. Explain how you can determine which traits above show incomplete
dominance or codominance.
4. In cattle, roan cattle are cattle that exhibit codominance of red and white
hair color alleles. Roan cattle have both red and white hairs expressed
FRFW. Which of the following cattle matings would produce the greatest
number of roan offspring:
Roan x Roan
Red x White
Red x Roan
White x Roan
Explain your answer.
5. Checkered chickens are the result of codominance between the black
feather allele (CB) and the white feathered allele (CW). Can there be a truebreeding strain of checkered chickens? Explain why or why not.
6. The curly hair (HC) and straight hair (HS) alleles exhibit codominance, to
produce a wavy hair phenotype for heterozygotes (HC HS). If a father has
straight hair, and a mother has wavy hair, what is the probability of
different hair phenotypes for their children?
Sperm
Egg
Phenotype Ratio:
______________________________
Probability of Curly Hair _________
Probability of Wavy Hair _________
Probability of Straight Hair ________
7. Blood type in humans is a trait that exhibits multiple alleles. There are
three possible alleles for the main blood marker gene: IA, IB and i. Alleles
IA and IB exhibit codominance. The allele i, for blood type O, is recessive.
For each of the following blood type phenotypes, determine the possible
genotypes.
Phenotype
A
B
AB
O
Possible Genotypes
________________
________________
________________
________________
8. In a maternity ward, Mrs. Bright and Mrs. Light share a room. When they
are ready to go home, Mrs. Bright insists she has been given the wrong
baby. Analyze the blood type evidence below to see if it supports,
disproves or is inconclusive in this maternity issue.
Blood Types
Mrs. Bright
AB
Mr. Bright
O
Baby at Bright’s house
O
Mrs. Light
A
Mr. Light
A
Baby at Light’s house
A
Possible Genotypes
________
________
________
________
________
________
Was there a mix-up of babies in the hospital? Explain your answer.
9. What are the possible blood types of the offspring between a father who is
blood type AB and a mother who is blood type O.
A. AB or O
D. A, B, AB or O
B. A, B or O
E. A, B or AB
C. A or B
Explain your answer.
10. What are the possible blood types of the offspring between a father who
is blood type A and a mother who is blood type B.
A. AB or O
D. A, B, AB or O
B. A, B or O
E. A, B or AB
C. A or B
Explain your answer.
In addition to the gene that controls the A, B, AB or O blood type, a second gene
in humans controls whether a person’s red blood cells have an Rh factor present.
Rh positive (R) is dominant over Rh negative (r).
Use the following information for questions 11-14. A woman who belongs to the
blood group A is Rh posititve. She has a daughter who is O positive and a son
who is B negative.
11. Which of the following is a possible genotype of the son?
A. IBIB rr
D. IBi rr
B. IBIB RR
E. IBIB Rr
B
C. I i Rr
12. Which of the following is a possible genotype of the mother?
A. IAIA RR
D. IAi Rr
B. IAIA Rr
E. IAi RR
A
C. I i rr
13. Which of the following is a possible phenotype for the father?
A. A negative
D. A positive
B. B negative
E. O positive
C. B positive
F. Either B or C
14. A man is brought to court for a paternity case. He has blood type B
positive. The mother has blood group B negative. The child has blood
type A negative. What can you say about the man’s chances of being the
father?
A. He is the father
C. He can not be the father
B. He might be the father D. He is unlikely to be the father