BIO 182 EXAM 2 PRACTICE QUESTIONS AND
DETAILED SOLUTIONS
◉ The phenotype of an individual
a. depends at least in part on the genotype.
b. is either homozygous or heterozygous.
c. determines the genotype.
d. is the genetic constitution of the organism.
e. is either monohybrid or dihybrid.
Answer: a. depends at least in part on the genotype.
◉ The ABO blood groups in humans are determined by a multiple-
allele system in which IA and
IB are codominant and are both dominant to IO. A newborn infant is
type A. The mother is type
O. Possible phenotypes of the father are
a. A, B, or AB.
b. A, B, or O.
c. O only.
d. A or AB.
e. A or O.
Answer: d. A or AB.
,◉ Which statement about an individual that is homozygous for an
allele is not true?
a. Each of its cells possesses two copies of that allele.
b. Each of its gametes contains one copy of that allele.
c. It is true-breeding with respect to that allele.
d. Its parents were necessarily homozygous for that allele.
e. It can pass that allele to its offspring..
Answer: d. Its parents were necessarily homozygous for that allele.
◉ Which statement about a test cross is not true?
a. It tests whether an unknown individual is homozygous or
heterozygous.
b. The test individual is crossed with a homozygous recessive
individual.
c. If the test individual is heterozygous, the progeny will have a 1:1
ratio.
d. If the test individual is homozygous, the progeny will have a 3:1
ratio.
e. Test cross results are consistent with Mendel's model of
inheritance for unlinked genes.
Answer: d. If the test individual is homozygous, the progeny will
have a 3:1 ratio
,◉ Linked genes
a. must be immediately adjacent to one another on a chromosome.
b. have alleles that assort independently of one another.
c. never show crossing over.
d. are on the same chromosome.
e. always have multiple alleles..
Answer: d. are on the same chromosome.
◉ In the F2 generation of a dihybrid cross
a. four phenotypes appear in the ratio 9:3:3:1 if the loci are linked.
b. four phenotypes appear in the ratio 9:3:3:1 if the loci are
unlinked.
c. two phenotypes appear in the ratio 3:1 if the loci are unlinked.
d. three phenotypes appear in the ratio 1:2:1 if the loci are unlinked.
e. two phenotypes appear in the ratio 1:1 whether or not the loci are
linked..
Answer: b. four phenotypes appear in the ratio 9:3:3:1 if the loci are
unlinked.
◉ The genetic sex of a human is determined by
a. ploidy, with the male being haploid.
b. the Y chromosome.
, c. X and Y chromosomes, the male being XX.
d. the number of X chromosomes, the male being XO.
e. Z and W chromosomes, the male being ZZ..
Answer: b. the Y chromosome.
◉ In epistasis
a. nothing changes from generation to generation.
b. one gene alters the effect of another.
c. a portion of a chromosome is deleted.
d. a portion of a chromosome is inverted.
e. the behavior of two genes is entirely independent.
Answer: b. one gene alters the effect of another.
◉ In humans, spotted teeth are caused by a dominant sex-linked
gene. A man with spotted teeth
whose father had normal teeth marries a woman with normal teeth.
Therefore,
a. all of their daughters will have normal teeth.
b. all of their daughters will have spotted teeth.
c. all of their children will have spotted teeth.
d. half of their sons will have spotted teeth.
e. all of their sons will have spotted teeth..
DETAILED SOLUTIONS
◉ The phenotype of an individual
a. depends at least in part on the genotype.
b. is either homozygous or heterozygous.
c. determines the genotype.
d. is the genetic constitution of the organism.
e. is either monohybrid or dihybrid.
Answer: a. depends at least in part on the genotype.
◉ The ABO blood groups in humans are determined by a multiple-
allele system in which IA and
IB are codominant and are both dominant to IO. A newborn infant is
type A. The mother is type
O. Possible phenotypes of the father are
a. A, B, or AB.
b. A, B, or O.
c. O only.
d. A or AB.
e. A or O.
Answer: d. A or AB.
,◉ Which statement about an individual that is homozygous for an
allele is not true?
a. Each of its cells possesses two copies of that allele.
b. Each of its gametes contains one copy of that allele.
c. It is true-breeding with respect to that allele.
d. Its parents were necessarily homozygous for that allele.
e. It can pass that allele to its offspring..
Answer: d. Its parents were necessarily homozygous for that allele.
◉ Which statement about a test cross is not true?
a. It tests whether an unknown individual is homozygous or
heterozygous.
b. The test individual is crossed with a homozygous recessive
individual.
c. If the test individual is heterozygous, the progeny will have a 1:1
ratio.
d. If the test individual is homozygous, the progeny will have a 3:1
ratio.
e. Test cross results are consistent with Mendel's model of
inheritance for unlinked genes.
Answer: d. If the test individual is homozygous, the progeny will
have a 3:1 ratio
,◉ Linked genes
a. must be immediately adjacent to one another on a chromosome.
b. have alleles that assort independently of one another.
c. never show crossing over.
d. are on the same chromosome.
e. always have multiple alleles..
Answer: d. are on the same chromosome.
◉ In the F2 generation of a dihybrid cross
a. four phenotypes appear in the ratio 9:3:3:1 if the loci are linked.
b. four phenotypes appear in the ratio 9:3:3:1 if the loci are
unlinked.
c. two phenotypes appear in the ratio 3:1 if the loci are unlinked.
d. three phenotypes appear in the ratio 1:2:1 if the loci are unlinked.
e. two phenotypes appear in the ratio 1:1 whether or not the loci are
linked..
Answer: b. four phenotypes appear in the ratio 9:3:3:1 if the loci are
unlinked.
◉ The genetic sex of a human is determined by
a. ploidy, with the male being haploid.
b. the Y chromosome.
, c. X and Y chromosomes, the male being XX.
d. the number of X chromosomes, the male being XO.
e. Z and W chromosomes, the male being ZZ..
Answer: b. the Y chromosome.
◉ In epistasis
a. nothing changes from generation to generation.
b. one gene alters the effect of another.
c. a portion of a chromosome is deleted.
d. a portion of a chromosome is inverted.
e. the behavior of two genes is entirely independent.
Answer: b. one gene alters the effect of another.
◉ In humans, spotted teeth are caused by a dominant sex-linked
gene. A man with spotted teeth
whose father had normal teeth marries a woman with normal teeth.
Therefore,
a. all of their daughters will have normal teeth.
b. all of their daughters will have spotted teeth.
c. all of their children will have spotted teeth.
d. half of their sons will have spotted teeth.
e. all of their sons will have spotted teeth..
