Download Incomplete and Codominance Problems

Incomplete and Codominance Problems
1. In the Manx cat the two alleles for tail are either a long tail or no tail. If one of each of
these genes is present the cat has a short tail. This is an example of incomplete
dominance, when hybrid genotype produces a completely different phenotype. What
would be the genotype and phenotype of the offspring between a long tailed cat and a cat
with no tail?
2. Give all the possible genotypes and the corresponding phenotypes for the offspring of a
cross between a short and a long tailed Manx cat. What are the chances that this cross
will produce a cat with no tail?
3. The andalusian chicken has a gene for black fathers and a gene for white fathers. When
one of each gene is present in the genotype, its phenotype is blue feathers. What are the
genotypic and phenotypic ratios of the offspring between two blue feathered chickens?
4. When a black feathered chicken is crossed with a blue feathered chicken, what are the
chances that the offspring will have black feathers? Blue feathers? White feathers?
5. A certain breed of cattle has a gene for white fur and another gene for red fur. The color
known as roan which is a reddish brown color is the result of one white and one red fur
gene being expressed. This is an example of codominance, when both genes are
expressed. Is it possible for a roan and a white cross to produce red cattle? Is it possible
for this pair to produce white offspring?
6. Two cattle were mated and 100% of the offspring were roan colored. What must have
been the genotypes of the P generation?
7. Japanese 4’O clock flowers can be homozygous red or homozygous white. The
heterozygous condition produces pink flowers. If the offspring from one cross produced
50% red flowers and 50% pink flowers what must have been the genotypes of the
original flowers?
8. 400 Japanese 4’O clock flowers were produced from the pollination between two specific
plants. 100 of these were red, 100 were white and 200 were pink. What were the colors of
the original flowers that were crossed?
9. The trait for the shape of a red blood cell can be either normal or sickle. Two sickle genes
must be present for the person to suffer from the disease sickle cell anemia. If someone
has one normal gene and one sickle gene for red blood cell shape that person is known as
a carrier or has sickle cell trait, but does not suffer from the disease. What are the chances
that the child of parents who are both sickle cell carriers will get the disease?
10. A girl is born with sickle cell anemia. Her father does not suffer from this disease and
neither does her mother. However, this girl’s grandmother has sickle cell anemia. Give
the genotypes of the girl, the mother, and father and the grandmother.