Multiple Allele Traits in Chickens
All chicken have combs on their heads, but it does not always look the same. The comb is a fleshy growth on the
top of the chicken's head. Both male and female chickens have combs, but the ones on the male are larger. Combs
of different breeds may look different in shape and even in color.
1. On the cross pictured, what must be the genotypes of the two parents for the outcome to always be a walnut
offspring?
____________ x _____________
2. Show a Punnett square for the following cross and describe the phenotypic ratios.
RrPp x RrPp
3. Show a punnett square for the following cross and describe the phenotypic ratios.
Single comb x Walnut (RrPp)
4. Show a punnett square for the following cross and describe the phenotypic ratios.
Single comb x Pea comb (rrPp)
5. A rose crossed with a pea produces six walnut and five rose offspring. What must be the genotypes of the
parents? Show the cross.
X-Linked Genetics in the Calico Cat
Calico is a coat color found in cats, which is caused by a SEX-LINKED, CODOMINANT allele.
B = Black
R = oRange
BR = calico
The following genotypes are possible;
Female cats can be black XBXB, orange XRXR, or calico XBXR
Male cats can be black XBY or orange XRY
Show each of the crosses below and include the phenotypic ratios of the offspring.
1.
A black male crossed with an orange female
2. An orange male crossed with a calico female
3. A black male crossed with a black female
4. An orange male crossed with an orange female
5. A black male crossed with a calico female
Genetics: Multiple Allele Traits
Blood Type
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? ____________________
Practice: Codominance and Incomplete Dominance
1. Practice setting up keys for the phenotypes listed in each set. Remember that the "medium" 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? ____________