Name: _______________________________ Date: _____________________
In horses, the allele for a bay coat (brown with black mane, tail and
legs) and the allele for a cream coat can combine to make a
buckskin coat.
The allele BB is used for bay; CC is used for cream. Buckskin
horses have one bay allele and one cream allele.
The genotype BC makes a buckskin coat, as neither allele is
dominant.
Buckskin
1. Cross a bay stallion with a cream mare. List all offspring phenotypes as a percentage. Show
your work with a Punnett square.
2. Cross two buckskin horses and list all possible phenotypes among offspring as a
percentage. Show your work with a Punnett square.
3. Bay, cream, and buckskin horse coats is an example of (circle one) codominance |
incomplete dominance.
Ball pythons have many inheritance patterns among the colors and patterns of their skin. One
example is the cross among a wild type (normal) ball python with a super pastel python. The
two produce a pastel python, which demonstrates incomplete dominance: a blend of the other
phenotypes.
Wild Type (normal)
NN
Super Pastel
PP
Pastel
NP
4. Use a Punnett square to predict the offspring ratios among a cross of two pastel ball
pythons.
Pigeons usually have scales on their feet, but in some circumstances, feathers are present
along with scales.
The feathers are referred to as “slipper feet”. When the allele for slipper feet is combined with
the allele for non-slipper feet (normal), the offspring will have some feathers on its feet, but not
as many as if it had inherited two slipper feet alleles.
The allele for slipper feet is SS, the allele for non-slipper feet is FF. If a pigeon carries one of
each allele, they have some feathers (SF).
5. Without doing a Punnett square, predict what percentages of
offspring the cross among a heterozygous slipper footed
pigeon and a non-slipper footed would create: ____________
__________________________________________________
____________________________________________.
6. Do a Punnett square to determine if your prediction was correct:
7. Pigeon “slipper feet” is an example (circle one) codominance | incomplete dominance.
In cows, white hairs and red hairs can both show up to form a roan pattern.
8. Make a key for the alleles of white hair, red hair, and roan.
White hair= _______
Red hair=_______ Roan hair=_______
9. If a roan sow and a roan bull mated, which percentage of their
offspring would be white?
10. If a roan sow gave birth to a roan calf, what are the possible phenotypes of the bull
(father)?
11. If you wanted to obtain 100% roan calves, what would the parents’ genotypes need to be?
12. The roan pattern in cattle is an example (circle one) codominance | incomplete dominance.
13. Describe the appearance that a baby calf would be if the red and white hairs were
incompletely dominant instead of codominant.