Name ………………………………
Hour ……
Incomplete Dominance
1. The genetics involved in human hair types are actually a bit
complicated, but for the sake of this example, let’s say that there are two
alleles- a straight hair allele (SS) and a curly hair allele (CC). Neither is
completely dominant and will produce a blended effect of having wavy
hair (CS).
CC
SS
CS
A. Napoleon, who has curly hair, and Summer, who has straight hair,
want to know what type of hair their offspring might have. Draw a
Punnett Square to find the possible offspring. What are the
expected ratios of F1 offspring phenotypes and genotypes?
B. If you crossed two F1 offspring, what percent of the F2 generation
would you expect to have straight hair?
2. If you cross a Hobbit with an Elf you get F1 offspring with slightly
pointy ears.
Elf-pointy ears(EE)
Hobbit-non-pointy ears(HH)
Elobbit-slightly pointy ears(EH)
Name ………………………………
Hour ……
Incomplete Dominance
A. If a Hobbit named Frodo did not have to toss the “one ring to rule
them all” into the depths of Mount Doom, he would have married a
nice Hobbit in the Shire. What percent of his offspring would you
expect to have non-pointy ears?
B. If the Hobbit, Frodo, married an Elf while in Rivendell, and then one
of his daughters with slightly pointy ears married one of Samwise
Gamgee (another Hobbit) and Arwen Evenstar’s (an Elf) sons that
also had slightly pointy ears, what percent of their children would
have ears like Frodo and Samwise?
3. Make up your own example of incomplete dominance. Draw pictures
of the three phenotypes of your organisms.
Show a Punnett Square for
a cross between the two homozygous types. List the phenotype and
genotype of the offspring.