Name _________________________________________ Date _______________
Incomplete Dominance Problems
1. A cross between a blue blahblah bird (B) & a white blahblah bird (W) produces offspring
that are silver. The color of blahblah birds is inherited by co-dominance.
a) What are the genotypes of the parent blahblah birds?
b) What is/are the genotype(s) of the silver offspring?
c) What would be the phenotypes of the offspring produced by two silver blahblah birds?
Draw a Punnett square to find your answer.
2. A very common phenotype used in questions about co-dominance is roan fur in cattle.
Cattle can be red (RR = all red hairs), white (WW = all white hairs), or roan (RW = red &
white hairs together).
a) Use a Punnett square to predict the phenotypic ratios of offspring when a white
cow is crossed with a roan bull.
b) What should the genotypes & phenotypes for parent cattle be if a farmer wanted only
cattle with red fur?
3. A cross between a black cat and a tan cat produces a tabby pattern (black & tan fur
together).
a) What pattern of inheritance does this show?
b) What percent of kittens would have tan fur if a tabby cat is crossed with a black cat?
Use a Punnett square to show how you found your answer.
Working Backwards- THINK!
4. The color of fruit for plant "X" is determined by two alleles. When two plants are crossed
the following phenotypic ratios are present in the offspring: 25% red fruit, 50% orange fruit,
25% yellow fruit. What are the genotypes and phenotypes of the parent fruit plants? Show
how you determined this using a Punnett square.