51. In humans an extra copy of chromosome 21 typically leads to moderate to severe mental retardation
and sterility, as well as a greater likelihood of heart defects and other problems. This disorder is known
as ____.
a.
Turner syndrome
b.
Down syndrome
c.
cri-du-chat
d.
Triple-X syndrome
e.
Klinefelter syndrome
52. Which of the following conditions would most likely lead to an apparently normal human female?
a.
Turner syndrome
b.
Down syndrome
c.
cri-du-chat
d.
Triple-X syndrome
e.
Klinefelter syndrome
53. Which genetic condition is revealed in the karyotype display shown in the figure above?
a.
Turner syndrome
b.
Down syndrome
c.
cri-du-chat
d.
Triple-X syndrome
e.
Klinefelter syndrome
54. About half of all flowering plant species, including many important crop plants, are ____.
a.
polyploids
b.
haploids
c.
aneuploids
d.
euploids
e.
diploids
55. About 10−15% of African Americans are carriers for ____, an autosomal recessive genetic disorder
where a defective version of hemoglobin is produced.
a.
Duchenne muscular dystrophy
b.
phenylketonuria
c.
achondroplasia
d.
sickle-cell disease
e.
cystic fibrosis
56. Carriers for sickle-cell disease have a genetic advantage in some situations over those who do not have
any copies of the sickle-cell allele because carriers have
a.
lower blood pressure.
b.
the ability to carry more oxygen in their blood.
c.
increased resistance to malaria.
d.
hyperactive immune systems.
e.
extra red blood cells.
57. About 4% of those of Northern European descent are carriers for ____, an autosomal recessive genetic
disorder where a defective membrane transport protein leads to abnormal chloride levels in
extracellular fluids.
a.
Duchenne muscular dystrophy
b.
phenylketonuria
c.
achondroplasia
d.
sickle-cell anemia
e.
cystic fibrosis
58. Most hospitals in the United States routinely test all newborns for this autosomal recessive disorder
where an enzyme in amino acid metabolism is not produced, leading to a buildup of compounds that
damage brain tissue and can lead to mental retardation unless a restricted diet is followed.
a.
Duchenne muscular dystrophy
b.
phenylketonuria
c.
achondroplasia
d.
sickle-cell anemia
e.
cystic fibrosis
59. This autosomal dominant genetic trait associated with a gene on human chromosome 4 leads to a type
of dwarfing due to defective cartilage formation.
a.
Duchenne muscular dystrophy
b.
phenylketonuria
c.
achondroplasia
d.
sickle-cell anemia
e.
cystic fibrosis
60. Which of the following has X-linked recessive inheritance?
a.
Duchenne muscular dystrophy
b.
phenylketonuria
c.
achondroplasia
d.
sickle-cell anemia
e.
cystic fibrosis
61. The percentage of children’s hospital patients being treated for problems arising from inherited
disorders is about
a.
1%.
b.
1% to 3%.
c.
5% to 10%.
d.
10% to 25%.
e.
70%.
62. As part of his or her job, a genetic counselor may do all of the following except
a.
analyze family pedigrees.
b.
advise a couple to have direct testing for altered proteins.
c.
advise a couple to have DNA testing.
d.
predict the chances of a couple having a child with a specific trait.
e.
tell a couple not to have children
63. You are genetic counselor, and a couple comes to you with concerns that if they have a child together
it could have cystic fibrosis. Genetic tests reveal that the woman is a carrier for cystic fibrosis but the
man is not. Which of the following would be a correct thing to tell them?
a.
Any child that they produce has a 50% chance of having cystic fibrosis, and the rest will
be carriers.
b.
All of their offspring will have cystic fibrosis.
c.
They should not have any concerns, as no child that they produce should wind up with
cystic fibrosis.
d.
No child that they produce should wind up with cystic fibrosis, but each of their offspring
will have a 50% chance of being a carrier.
e.
Any child that they produce will have a 25% chance of having cystic fibrosis.
64. You are genetic counselor, and a couple comes to you with concerns that if they have a child together
it could have sickle-cell disease. Genetic tests reveal that the man and woman are both carriers for
sickle-cell disease. Which of the following would be a correct thing to tell them?
a.
Any child that they produce has a 50% chance of having sickle-cell disease, and the rest
will be carriers.
b.
All of their offspring will have sickle-cell disease.
c.
They should not have any concerns, as no child that they produce should wind up with
sickle-cell disease.
d.
No child that they produce should wind up with sickle-cell disease, but each of their
offspring will have a 50% chance of being a carrier.
e.
Any child that they produce will have a 25% chance of having sickle-cell disease.
65. Prenatal diagnosis techniques such as amniocentesis and chorionic villus sampling remove cells that
were produced by an embryo. These cells are then used
a.
to treat diseases.
b.
for implantation to produce pregnancy.
c.
to develop embryonic stem cells.
d.
to test for the presence of mutant alleles or chromosomal alterations.
e.
for cloning.
66. A mutation in the human gene for a fibroblast growth factor receptor (FGFR) appears to be responsible
for ____.
a.
Duchenne muscular dystrophy
b.
phenylketonuria
c.
achondroplasia
d.
sickle-cell anemia
e.
cystic fibrosis
67. Cytoplasmic inheritance refers to genes found in
a.
sex chromosomes.
b.
mitochondria and chloroplasts.
c.
viruses.
d.
bacteria.
e.
only one parent.
68. For most multicellular eukaryotes, including humans, mitochondria are inherited
a.
only from the father.
b.
from both the father and the mother.
c.
from the mother for females and from the father for males.
d.
randomly from either the father or the mother.
e.
only from the mother.
69. The expression of only one allele of a gene and silencing of the other allele, all based on which parent
contributed each allele, is
a.
sex-linked inheritance.
b.
uniparental inheritance.
c.
cytoplasmic inheritance.
d.
genomic imprinting.
e.
maternal inheritance.
70. Prader-Willi syndrome and Angelman syndrome are both caused by the same genetic deletion on
human chromosome 15, but they have very different phenotypes. Which disorder occurs depends upon
which parent provided the chromosome with the deletion. This is an example of
a.
sex-linked inheritance.
b.
uniparental inheritance.
c.
cytoplasmic inheritance.
d.
genomic imprinting.
e.
maternal inheritance.
71. The molecular mechanism that produces genomic imprinting by inactivating an allele involves ____ of
DNA in the allele that will not be expressed.
a.
methylation
b.
mutation
c.
ligation
d.
deletion
e.
inversion
72. Cancers associated with mammalian insulin growth factor 2 (IGf2) typically result from
a.
translocations.
b.
X-inactivation.
c.
inversions.
d.
duplications.
e.
loss of imprinting.
73. Genetic recombination in somatic cells is used to
a.
produce variability in offspring.
b.
determine cell types during development.
c.
repair damaged or broken chromosomes.
d.
produce specialized tissues in organs.
e.
establish the sex of the individual.
74. Examine the pedigree in the figure above, where individuals that have the genetic condition being
tested are marked with filled squares or circles. Which of the following inheritance patterns is most
likely correct for this condition?
a.
autosomal dominant
b.
X-linked recessive
c.
X-linked dominant
d.
cytoplasmic inheritance
e.
autosomal recessive
75. Examine the pedigree in the figure above, where individuals that have the genetic condition being
tested are marked with filled squares or circles. Which of the following inheritance patterns is most
likely correct for this condition?
a.
autosomal dominant
b.
X-linked recessive
c.
X-linked dominant
d.
cytoplasmic inheritance
e.
autosomal recessive
76.
Examine the pedigree in the figure above, where individuals that have the genetic condition being
tested are marked with filled squares or circles. Which of the following inheritance patterns is most
likely correct for this condition?
a.
autosomal dominant
b.
X-linked recessive
c.
X-linked dominant
d.
cytoplasmic inheritance
e.
autosomal recessive
77. Examine the pedigree in the figure above, where individuals that have the genetic condition being
tested are marked with filled squares or circles. Which of the following inheritance patterns is most
likely correct for this condition?
a.
autosomal dominant
b.
X-linked recessive
c.
X-linked dominant
d.
cytoplasmic inheritance
e.
autosomal recessive
78. You are a genetic counselor, and a couple comes to you with concerns that if they have a child
together it could have hemophilia. The man has an X-linked recessive form of hemophilia, but the
woman does not. Genetic tests reveal the woman is not a carrier for hemophilia. Which of the
following would be a correct thing to tell them?
a.
Any child that they produce will have a 50% chance of having hemophilia.
b.
All of their male offspring will have hemophilia, and each of their female offspring will
have a 50% chance of having hemophilia.
c.
None of their offspring should have hemophilia, but all of their female offspring will be
carriers for hemophilia.
d.
Each of their male offspring will have a 50% chance of having hemophilia, and while their
female offspring should not have hemophilia, they will each have a 50% chance of being
carriers.
e.
All of their male offspring will have hemophilia, and while their female offspring should
not have hemophilia, they will all be carriers.
79. You are a genetic counselor, and a couple comes to you with concerns that if they have a child
together it could have hemophilia. The woman has an X-linked recessive form of hemophilia, but the
man does not. Which of the following would be a correct thing to tell them?
a.
Any child that they produce will have a 50% chance of having hemophilia.
b.
All of their male offspring will have hemophilia, and each of their female offspring will
have a 50% chance of having hemophilia.
c.
None of their offspring should have hemophilia, but all of their female offspring will be
carriers for hemophilia.
d.
Each of their male offspring will have a 50% chance of having hemophilia, and while their
female offspring should not have hemophilia they will each have a 50% chance of being
carriers.
e.
All of their male offspring will have hemophilia, and while their female offspring should
not have hemophilia, they will all be carriers.
80. You are a genetic counselor, and a couple comes to you with concerns that if they have a child
together it could have hemophilia. Neither one of them has hemophilia, but the woman’s biological
father did have an X-linked recessive form of hemophilia. Which of the following would be a correct
thing to tell them?
a.
Any child that they produce will have a 50% chance of having hemophilia.
b.
All of their male offspring will have hemophilia, and each of their female offspring will
have a 50% chance of having hemophilia.
c.
None of their offspring should have hemophilia, but all of their female offspring will be
carriers for hemophilia.
d.
Each of their male offspring will have a 50% chance of having hemophilia, and while their
female offspring should not have hemophilia, they will each have a 50% chance of being
carriers.
e.
All of their male offspring will have hemophilia, and while their female offspring should
not have hemophilia, they will all be carriers.
291
MATCHING
Choice
Choose the mode of inheritance that has been determined for each of the following genetic conditions
in humans.
a.
autosomal recessive
b.
autosomal dominant
c.
X-linked recessive
d.
aneuploidy
e.
genomic imprinting
81. Down syndrome
82. achondroplasia
83. sickle-cell disease
84. Angelman syndrome
85. phenylketonuria
86. Duchenne muscular dystrophy
87. cystic fibrosis
88. red-green colorblindness
89. progeria
SHORT ANSWER
90. Suppose that you have discovered a new mutant in Drosophila melanogaster. What kinds of genetic
crosses should you do to determine if the allele causing the mutation is inherited as an autosomal
dominant trait, an autosomal recessive trait, or a sex-linked trait?
91. Two genes are on the same chromosome, yet crossing over occurs between them every time meiosis
occurs. Are these genes linked or unlinked and why?
92. Explain the difference in meiotic products that arise from a meiosis in which nondisjunction occurs
during the first division and a meiosis in which nondisjunction occurs during the second division.
93. It has been known for some time that fetal cells can be found in a pregnant woman’s bloodstream,
sometimes years after a pregnancy. A new technique has been developed that allows scientists to
isolate these fetal cells from a pregnant woman’s blood. Why would this be a useful new tool for
parents interested in genetic testing of their fetus?
94. A certain disorder appears to be inherited from mother to child. What are two possible modes of
inheritance for this disorder?
ESSAY
95. You are working in a research lab on the organism Drosophila melanogaster and you have been given
the job of determining the relative positions of three linked genes for your undergraduate research
project. A graduate student in the lab tells you that gene a is 5.0 centimorgans from gene b, and that
gene c is 2.7 centimorgans from gene b. What should you do to finish mapping these three genes?
What are the likely results that may occur, and how would you interpret such results?
96. Your cousin finds out that she is a carrier for phenylketonuria. Also, her husband’s biological mother
has phenylketonuria. She asks you to explain what this could mean if she and her husband have
children and asks what, if anything, could be done to best protect any child that they have. What would
you tell her?
97. Turner Syndrome (XO) is the only viable monosomy found in humans. Some sex chromosome
trisomies are also viable, including XXX, XXY, and XYY. There are no viable autosomal
monosomies, and a small handful of viable autosomal trisomies exist, such as Trisomy 21 (Down
Syndrome), and Trisomy 13 and 18, both of which are lethal within the first year of life. Clearly
aneuploidy is not tolerated well in humans. Speculate as to why there are so few viable monosomies
(only one) in humans, and then why there are so few viable trisomies. Also, speculate as to why
aneuploidy involving the sex chromosomes is better tolerated than those involving autosomes.