AP Biology
Heredity Quest Study Guide
1. Vocabulary – new terms
a. Codominant alleles
b. Incompletely dominant alleles
c. Pleiotropic alleles
d. Hemizygous
e. Epistasis
f. Autosome
g. Sex-chromosome
h. Linked genes
i. Recombinants
j. Crossing-over
k. Pedigree
2. Practice problems
a. One factor cross – describe phenotype/genotype ratios of the following
crosses (A = Tall, a = short – A is completely dominant)
i. AA x aa (test cross)
ii. Aa x aa (test cross)
iii. Aa x Aa (monohybrid cross)
b. Two factor cross - describe phenotype/genotype ratios of the following
crosses (A = Tall, a = short; B = Brown eyes, b = blue eyes – A & B are
completely dominant)
i. AaBb x AaBb (dihybrid cross)
c. For following cross, describe the likelihood the offspring shown:
i. AABbcc x aaBbCC  AabbCc
ii. AaBbCcDd x aabbccdd  aabbccdd
d. Given the following information:
A normal woman marries a hemophiliac male. They have 12 kids: 3 normal
girls, 4 normal boys, 2 hemophiliac boys, and 3 hemophiliac girls.
i. What are the genotypes of the parents? Draw a Punnett Square to
verify your hypothesis.
ii. Use a Chi-square test on the data to analyze your prediction of the
parental genotypes. Show all your work and explain the
importance of your final answer.
Formula for Chi-square 2 =  ((o-e)2/e); o = observed; e = expected
Critical Values for Chi-square distribution
Probability (p)
Degrees of Freedom (df)
1
2
3
0.05
3.84
5.99
7.82
4
9.49
e. Mary has blood type A, John has blood type AB, Phil has blood type O,
Mary’s dad has blood type O.
i. What is Mary’s genotype?
ii. Mary has a baby with Phil. What is the likelihood the baby will be
blood type O?
iii. If she has a baby with John, what is the likelihood the baby will
have blood type A? Type O?
f. Fred has type AB blood, Wilma has type B blood, and Pebbles, their
daughter has type A blood. Betty has type B blood, Barney has type A
blood, and their some BamBam has type O blood. In the bloodiest fight
ever witnessed in Bedrock, BCE, Barney accused Betty of having an affair
with Fred. Barney also claimed that Fred is BamBam’s father, sighting
evidence from the new field of Geneticsrock. Could Barney be right?
Could Fred be BamBam’s father? Support your answer.
g. A rooster with blue (actually gray) feathers is mated with a hen of the
same phenotype. Among their offspring, 15 chicks are blue, 6 are black,
and 8 are white.
i. What is the simplest explanation for the inheritance of these colors
in chickens?
ii. What offspring would you predict from the mating of blue rooster
and a black hen?
h. The following recombination frequencies were found. Determine the order
of these genes on the chromosome.
a—c 10%
b—c 4%
c—d 20%
a—d 30%
b—d 16%
a—e 6%
b—e 20%