Name:
Period
Date
Complex Inheritance Patterns Worksheet
Directions: Complete the following questions in the space provided.
1. Distinguish between incomplete dominance and codominance.
2. A plant that produces white flowers is crossed with a plant that produces purple flowers. Describe the
phenotype of the offspring if the inheritance pattern for flower color is
a. incomplete dominance
b. codominance
3. In a cross between individuals of a species of tropical fish, all of the male offspring have long tail fins, and
none of the females possess the trait. Mating two of the F1 fish (the offspring from the first generation) fails
to produce females with the trait. Explain the inheritance pattern of the trait.
4. Suppose you mate a black rooster with a white hen. The feathers of all the offspring are black. Explain the
inheritance pattern in these chickens. Draw all possible Punnett Squares.
1
5. In cats, the allele for fur color is sex linked. The allele for black fur is XC, and the allele for orange fur is Xc .
From this information, explain why calico (mixed color) cats, XCXc, are always female.
6. Julia purchased a puppy from a breeder. The breeder explained that the puppy should never be bred with
another dog because it was a carrier. What did the breeder mean by this statement?
7. If a man has type AB blood and a woman has type A blood, what possible blood types could their children
have?
8. A baby has blood type AB. If the baby’s mother has blood type B, what blood type(s) could the father have?
9. A couple just brought home their new baby from the hospital. They begin to suspect that the hospital
switched babies, and the baby they brought home is not theirs. They check the hospital records, and find
that the man’s blood type is B, the woman’s blood type is AB, and the baby’s blood type is O. Explain why
the parents are or are not justified in their concern about this baby.
10. Four children have the following blood types: A, B, AB, and O. Could these children have the same two
biological parents? Explain.
2
11. In dogs, coat color is determined by the interaction between three alleles. The allele A produces a dark
colored dog, y produces a sandy colored dog, and t produces a spotted dog. The order of dominance is A >
y > t. Determine the following from the pedigree below.
a. the genotypes of the parents (I-1 and I-2)
b. the probability of an off spring from the mating between individuals II-2 and II-3 having spots
c. the possible genotypes of individual II-1
12. Determine the probability that a woman who is a carrier for hemophilia and a man without hemophilia will
have a child with hemophilia.
13. A woman with hemophilia and a man without hemophilia decide to have children. What is the probability
that their sons will have hemophilia?
3
14. Nystagmus is a condition in which involuntary eye movement leads to poor vision. This condition is caused
by an X-linked recessive allele. Suppose that a man and woman, both with normal vision, have two
children. The boy is affected with nystagmus, and the girl is unaffected.
a. Determine the genotype of the parents.
b. Is it possible to determine the genotypes of the children? Why or why not?
4