Problem #1
In Japanese four o'clock plants red (R) color is incompletely dominant over white (r) flowers, and the heterozygous
condition (Rr) results in plants with pink flowers. For each of the following construct a Punnett square and give the
genotypic and phenotypic ratios of the offspring
a) a red plant and a white plant
b) a red plant and a pink plant
c) a white plant and a pink plant .
d) two pink plants
Problem #2:
In some cats the gene for tail length shows incomplete dominance. Cats with long tails have the genotype "LL". Cats
with short tails are "LI", while cats with no fails at all are "il". For each of the following construct a Punnett square
and give the genotypic and phenotypic ratios of the offspring.
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
Co-Dominance Practice Problems:
Problem 1:
In some cattle the genes for brown hair and for white hair are co-dominant, Cattle with alleles for both brown and
white hair, have both brown and white hairs. This condition gives the cattle a reddish color, and is referred to as
Roan.
For each of the following construct a Punnett square and give the genotypic and phenotypic ratios of the offspring
a) a red cow and a white bull
b) a red cow and a roan bull
c) a white cow and a roan bull
d) a roan cow and a roan bull
Problem 2: (multiple alleles and co-dominance)
Blood types are controlled by three alleles A, B, O. A and B are co-dominants and O is recessive to both A and B.
The following genotypes and resultant phenotypes are possible:
Type A blood can have these genotypes: I^I^ and I'i
Type B blood can have these genotypes: I'I and Ii
Type AB (universal recipient) can have this genotype:I^
Type 0 (universal donor) can have this genotype: ii
a) A woman homozygous for blood type B marries a man that is heterozygous for blood type A. What are the
possible blood types of the offspring?
b) A man with blood type o marries a woman with blood type AB. State the possible blood types of the offspring.
c) A type B woman whose mother was type o marries a type o man. What are the possible blood types of their
offspring?
d) A type A woman whose father was type B marries a type B man whose mother was type A. What are the possible
blood types of their offspring?
e) What is the probability that a couple whose blood types are AB and will have a type A child?