Name:
Codominance and Incomplete Dominance Punnet Squares
1. If a red Japanese four-o’clock flower is crossed with a white one, all the
offspring will be pink. Perform each of the crosses below. And indicate the
colors of the plants
A. white plant crossed with a pink plant
B. red plant crossed with a pink plant
C. two pink plants are crossed
D. two red plants are crossed
2. In some cats the gene for tail length shows incomplete dominance. Cats with
long tails and those with no tails are homozygous for the respective alleles.
Cats with one long-tail allele and one no-tail allele have short tails. Perform
the crosses below and indicate the type of tail each cat would have.
A. a long tail cat and a cat with no tail
B. a long tail cat and a short tail cat
C. a short tail cat and a cat with no tail
D. two short tail cats
3. Fruit color in summer squash can be white, yellow, or green. A parental cross
of true breeding white and yellow fruit varieties result in all green fruits, if
two green fruit plants are mated, what are the possible offspring?
4. Mating between palomino horses yields an overall phenotypic ratio among
their offspring of 1 chestnut: 2 palomino: 1 cremello. Predict the outcome of
the following crosses:
A. palomino X chestnut
B. palomino X cremello
C. cremello X cremello
Name:
5. Two short tailed (Manx cats) are bred and produce three kittens with long
tails, five kittens with short tails and one kitten with no tail. Show how this is
possible.
6. In short horned cattle, coat color is codominant. A heterozygous individual
will have a coat color with a mixture of red and white hairs, called roan. If a
white cow is crossed with a roan bull, what types of offspring are expected?
7. What would result from the cross of 2 roan cattle?
8. The blue Andalusian variety of chickens has slate blue feathers, which are
really speckled black and white. This variety is produced when birds with
white feathers are mated with birds with black feathers. A farmer wants all
black chickens. He has two blue chickens to begin with. Show how he could
develop a pure black breeding chicken farm.
9. Use your imagination…a pink circus elephant finds a purple circus elephant
to marry. Imagine the ringmaster’s surprise when he sees two babies, pink
and purple spotted elephants. Show the genotypes of the parents and the
children. The spotted elephants are a big hit and the ringmaster thinks he can
mate the two spotted elephants to make a family of spotted elephants. Show
genetically if this possible or is he nuts.
Name:
10. Red blood cells that are crescent shaped are called sickle cells and are
present in individuals with sickle cell anemia. Individuals who are
homozygous for sickle cell produce only sickle shaped cells and have severe
anemia. Individuals who are heterozygous produce both normal and sickle
shaped cells and have a mild case of anemia. What are the chances of a couple
that both suffer from the mild form of sickle cell anemia to have normal
children?