Download Incomplete and Codominance worksheet

NAME____________________________________________________________________________________PERIOD______
HOMEWORK:
Incomplete Dominance and Codominance Worksheet
REMEMBER YOUR KEY!
Example (incomplete dominance):
KEY
FR = RED flowers
FW= WHITE flowers
EXAMPLE for writing out probabilities:
GENOTYPE: 1 FRFR : 2 FRFW : 1 FWFW
(OR, ratio is 1:2:1)
PHENOTYPE: 1 RED : 2 PINK : 1 WHITE
1. Cat fur color is determined by codominance.
The allele for tan fur (FTFT) and the allele for black fur (FBFB) are codominant.
The heterozygous condition (FTFB) results in a cat with tan and black spots, called a
tabby cat. What would occur is a tan cat was crossed with a
tabby cat?
a. Draw the Punnett square.
b. Include a KEY for the alleles (dominant/recessive, phenotypes)
c. Write out the probability for each genotype and phenotype.
2. If two tabby cats are crossed with each other, what is the probability that they’ll
have a tabby kitten? A black kitten? Draw the Punnett square to support your
answer.
3. In humans, hair type is determined by incomplete dominance.
Some people have curly hair (HCHC), some people have straight
hair (HSHS), and heterozygotes have wavy hair (HCHS). What would
occur if a person with wavy hair had a baby with a person with
straight hair?
a. Draw the Punnett square.
b. Include a KEY for the alleles (dominant/recessive, phenotypes)
c. Write out the probability for each genotype and phenotype.
4. If two people with wavy hair have a baby together, what is the likelihood that they’ll
have a curly haired baby? A straight-haired baby? Draw the Punnett square to
support your answer.
5. Sickle cell anemia is a trait that exhibits codominance.
A person with an CACA genotype does not have sickle cell anemia, and
a person with an CSCS genotype has full sickle cell anemia. A person
with a CACS genotype will have some sickle-cells, though s/he might
show minimal or no symptoms (a “carrier”).
Englebert is a carrier for sickle-cell anemia (shows minimal
symptoms), and his partner, Gwendoline, does not have it. What are the chances that
Engelbert and Gwendoline will have a child with ANY sickle-shaped blood cells?
a. Draw the Punnett square.
b. Include a KEY for the alleles (dominant/recessive, phenotypes)
c. EXPLAIN: What are the chances that Engelbert and Gwendoline will have a child
with ANY sickle-shaped blood cells?
6. In a species of birds, incomplete dominance between alleles for black (FB) and white
(FW) feathers is observed. Heterozygotes are blue. If two blue birds are crossed, what
will be the possible genotypes and phenotypes of the offspring?
7. Type A (IA) and Type B (IB) blood are codominant to each other.
They are both dominant over Type O (IO) blood. What are the
possible blood types for the offspring produced by a type “O”
mother and a Type “AB” father?
a. Draw the Punnett square.
b. Include a KEY for the alleles (dominant/recessive, phenotypes)
c. Write out the probability for each genotype and phenotype.
8. Mrs. Clink is type “A” and Mr. Clink is type “O.” They have three children named
Matthew, Mark, and Luke. Mark is type “O,” Matthew is type “A,” and Luke is type
“AB.” Based on this information:
a. Which child can NOT be the genetic offspring of these parents?
b. Mr. Clink must have the genotype ______
c. Mrs. Clink must have the genotype ______ because ___________ has blood
type ______
DRAW THE PUNNETT SQUARE (AND KEY) TO SUPPORT YOUR ANSWERS: