Download Practice: Codominance and Incomplete Dominance

Name: ______________________________ Date: _____________
Practice: Codominance and Incomplete Dominance
1. Practice identifying genotypes for the phenotypes listed in each set. Remember that the
"intermediate" trait must always be heterozygous.
a) Birds can be blue, white, or white with blue-tipped feathers.
b) Flowers can be white, pink, or red.
c) A Hoo can have curly hair, spiked hair, or a mix of both curly and spiked.
d) A Sneech can be tall, medium, or short.
e) A Bleexo can be spotted, black, or white.
2. Now, can you figure out in the above list, which of the letters represent codominant traits and which
are incomplete.
Codominant _____________ Incompletely Dominant ________________
3. In Smileys, eye shape can be starred, circular, or a circle with a star. Write the genotypes for the
pictured phenotypes
4. Show the cross between a star-eyed and a circle eyed.
What are the phenotypes of the offspring? ____________
What are the genotypes? __________
5. Show the cross between a circle-star eyed, and a circle eyed.
How many of the offspring are circle-eyed? ____________
How many of the offspring are circle-star eyed? ____________
6. Show the cross between two circle-star eyed.
How many of the offspring are circle-eyed? ____________
How many of the offspring are circle-star eyed? ____________
How many are star eyed? ____________
Genetics: Multiple Allele Traits
Blood type is controlled by 3 alleles: A, B, O. A & B are codominant, O is recessive.
1. a) What are the two genotypes possible for a person who as A blood? ______________
b) What genotype does a person with AB blood have? _______________
c ) What genotype does a person with O blood have? _____________
d) What are the two genotypes possible for a person who as B blood? ______________
2. A man with type AB blood is married to a woman also with type AB blood. What percentage of their
children will have:
A blood? _______ B blood? ______ O blood _____ AB blood ________
3. A man has type B blood (genotype BB) is married to a woman with type O blood. What blood type
will all their children have? ________ What is the genotype of the children? ______
4. A woman with type A blood (genotype AO) is married to a type B person (genotype BO). What
proportion of their children will have:
A blood? _______ B blood? ______ O blood _____ AB blood ________
5. A woman with type A blood is claiming that a man with type AB blood is the father of her child who
is type B.
Could this man be the father of the child? _______________ Show the possible crosses; remember
that the woman can have AA or AO genotypes.
Assuming that he is the father, what must the mother's genotype be? _____
6. A man with type AB blood is married to a woman with type O blood. They have two natural children
and one adopted child. Jane has type A blood, Bobby has type B blood, and Grace has type O blood.
Which child was adopted? ____________________
SMILEYS GENETICS
Determine the genotypes of the following Sunnys. It is a multiple allele trait, spiked and circles are
codominant and the bare trait is recessive.
12. Show genotypes
13. If a spiked sunny (heterozygous) is crossed with a bare sunny, what percentage of the offspring
will be bare? __________
What percentage will be spiked? ___________
14. If a spike-circle sunny is crossed with a heterozygous spike sunny, how many of the offspring will
be spiked? ______________
How many will be circles? ___________
How many will be spike-circles? ________________
15. A female sunny who is spiked is married to a male sunny who is circle. They have a child who is
bare. What must be the genotypes of the two parents? __________________
Genetics - X Linked Genes
**In fruit flies, eye color is a sex linked trait. Red is dominant to white.**
1. What are the sexes and eye colors of flies with the following genotypes?
X R X r _________ X R Y __________ X r X r __________
X R X R ____________ X r Y ____________
2. What are the genotypes of these flies:
white eyed, male ____________ red eyed female (heterozygous) ________
white eyed, female ___________ red eyed, male ___________
3. Show the cross of a white eyed female X r X r with a red-eyed male X R Y .
4. Show a cross between a pure red eyed female and a white eyed male.
What are the genotypes of the parents:
___________ and _______________
How many are:
white eyed, male ____
white eyed, female ____
red eyed, male ____
red eyed, female ____
5. Show the cross of a red eyed female (heterozygous) and a red eyed male.
What are the genotypes of the parents?
___________ & ________________
How many are:
white eyed, male ____
white eyed, female ____
red eyed, male ____
red eyed, female ____
Math: What if in the above cross, 100 males were produced and 200 females. How many total redeyed flies would there be? ________
Human Sex Linkage
6. In humans, hemophilia is a sex linked trait. Females can be normal, carriers, or have the disease.
Males will either have the disease or not (but they won’t ever be carriers)
X H X H = female, normal
X H X h = female, carrier
X h X h = female, hemophiliac
X H Y = male, normal
X h Y= male, hemophiliac
Show the cross of a man who has hemophilia with a woman who is a carrier.
What is the probability that their children will have the disease? __________
7. A woman who is a carrier marries a normal man. Show the cross. What is the probability that their
children will have hemophilia? What sex will a child in the family with hemophilia be?
8. A woman who has hemophilia marries a normal man. How many of their children will have
hemophilia, and what is their sex?
Calico Cat Genetics
9. In cats, the gene for calico (multicolored) cats is codominant. Females that receive a B and an R
gene have black and orange splotches on white coats. Males can only be black or orange, but never
calico.
Here’s what a calico female’s genotype would look like: X B X R
Show the cross of a female calico cat with a black male?
What percentage of the kittens will be black and male? _________
What percentage of the kittens will be calico and male? _________
What percentage of the kittens will be calico and female? _________
10. Show the cross of a female black cat, with a male orange cat.
What percentage of the kittens will be calico and female? _____What color will all the male cats be?
______