Understanding Pathophysiology 7th Ed.

Question 1

1-01. A student is observing a cell under the microscope. It is observed to have supercoiled DNA
with histones. Which of the following would also be observed by the student?
a. A single circular chromosome
b. A nucleus
c. Free-floating nuclear material
d. No organelles

Answer 1

ANS: B
The cell described is a eukaryotic cell, so it has histones and a supercoiled DNA within its
nucleus; thus, the nucleus should be observed. A single circular chromosome called a
prokaryote contains free-floating nuclear material but has no organelles.

Question 2

1-02. A nurse is instructing the staff about cellular functions. Which cellular function is the nurse
describing when an isolated cell absorbs oxygen and uses it to transform nutrients to energy?
a. Metabolic absorption
b. Communication
c. Secretion
d. Respiration

Answer 2

ANS: D
The cell’s ability to absorb oxygen is referred to as respiration while its communication ability
involves maintenance of a steady dynamic state, metabolic absorption provides nutrition, and
secretion allows for the synthesizing of new substances.

Question 3

1-03. A eukaryotic cell is undergoing DNA replication. In which region of the cell would most of
the genetic information be contained?
a. Mitochondria
b. Ribosome
c. Nucleolus
d. Nucleus cytoplasm

Answer 3

ANS: C
The region of the cell that contains genetic material, including a large amount of ribonucleic
acid, most of the DNA, and DNA-binding proteins, is the nucleolus, which is located within
the cell’s nucleus. Mitochondria is associated with cellular respiration while ribosomes are
involved with protein manufacturing. Cytoplasm is a fluid filling that is a component of the
cell.

Question 4

1-04. Which of the following can remove proteins attached to the cell’s bilayer by dissolving the
layer itself?
a. Peripheral membrane proteins
b. Integral membrane proteins
c. Glycoproteins
d. Cell adhesion molecules

Answer 4

ANS: B
Proteins directly attached to the membrane bilayer can be removed by the action of integral
membrane proteins that dissolve the bilayer. Peripheral membrane proteins reside at the
surface while cell adhesion molecules are on the outside of the membrane. Glycoprotein
marks cells and does not float.

Question 5

1-05. Which of the following can bind to plasma membrane receptors?

a. Oxygen
b. Ribosomes
c. Amphipathic lipids
d. Ligands

Answer 5

ANS: D

Ligands are the only specific molecules that can bind with receptors on the cell membrane.

Question 6

1-06. A nurse is reviewing a report from a patient with metastatic cancer. What alternation in the
extracellular matrix would support the diagnosis of metastatic cancer?
a. Decreased fibronectin
b. Increased collagen
c. Decreased elastin
d. Increased glycoproteins

Answer 6

ANS: A
Only a reduced amount of fibronectin is found in some types of cancerous cells, allowing
them to travel or metastasize.

Question 7

1. 7. Which form of cell communication is used to relate to other cells in direct physical contact?
      a. Cell junction
      b. Gap junction
      c. Desmosome
      d. Tight junction

Answer 7

ANS: A
Cell junctions hold cells together and permit molecules to pass from cell to cell. Gap junctions
allow for cellular communication between cells. Neither desmosomes nor tight junctions are
associated with cellular communication.

Question 8

1-08. Pancreatic beta cells secrete insulin, which inhibits secretion of glucagon from neighboring
alpha cells. This action is an example of which of the following signaling types?
a. Paracrine
b. Autocrine
c. Neurohormonal
d. Hormonal

Answer 8

ANS: A
Paracrine signaling involves the release of local chemical mediators that are quickly taken up,
destroyed, or immobilized, as in the case of insulin and the inhibition of the secretion of
glucagon. None of the other options involve signaling that is associated with a local chemical
mediator like insulin.

Question 9

1-09. In cellular metabolism, each enzyme has a high affinity for a:

a. solute.
b. substrate.
c. receptor.
d. ribosome.

Answer 9

ANS: B
Each enzyme has a high affinity for a substrate, a specific substance converted to a product of
the reaction. Cellular metabolism is not dependent on an attraction between an enzyme and
any of the remaining options.

Question 10

1-10. An athlete runs a marathon, after which his muscles feel fatigued and unable to contract. The
athlete asks the nurse why this happened. The nurse’s response is based on the knowledge that
the problem is result of a deficiency of:
a. GTP.
b. AMP.
c. ATP.
d. GMP.

Answer 10

ANS: C
When ATP is deficient, impaired muscle contraction results. None of the other options are
involved in muscle contraction.

Question 11

1-11. Which phase of catabolism produces the most ATP?

a. Digestion
b. Glycolysis
c. Oxidation
d. Citric acid cycle

Answer 11

ANS: D
While some ATP is produced during the oxidation and glycolysis phases, most of the ATP is
generated during the citric acid cycle. Digestion does not produce any ATP.

Question 12

1-12. A nurse is teaching the staff about the phases of cellular catabolism. Which phases should the
nurse include?
a. Digestion, glycolysis, oxidation, and the citric acid cycle
b. Diffusion, osmosis, and mediated transport
c. S phase, G phase, and M phase
d. Metabolic absorption, respiration, and excretion

Answer 12

ANS: A
Only digestion, glycolysis, oxidation, and the citric acid cycle are the phases of cellular
catabolism.

Question 13

1-13. A runner has depleted all the oxygen available for muscle energy. Which of the following will
facilitate his continued muscle performance?
a. Electron-transport chain
b. Aerobic glycolysis
c. Anaerobic glycolysis
d. Oxidative phosphorylation

Answer 13

ANS: C
When no oxygen is available, anaerobic glycolysis occurs. The electron-transport chain is part
of the citric acid cycle. Aerobic glycolysis involves the presence of oxygen. Oxidative
phosphorylation is the mechanism by which the energy produced from carbohydrates, fats,
and proteins is transferred to ATP. It is not part of muscle performance.

Question 14

1-14. A faculty member asks a student to identify the appropriate term for the movement of a solute
from an area of greater to lesser concentration. Which answer indicates the nursing student
understood the teaching?
a. Osmosis
b. Diffusion
c. Hydrostatic pressure
d. Active transport

Answer 14

ANS: B
Diffusion is the movement of a solute molecule from an area of greater solute concentration to
an area of lesser solute concentration through a permeable membrane. Osmosis is the
movement of water across a semipermeable membrane from a region of higher water
concentration to one of lower concentration. Hydrostatic pressure is the force of fluid against
a cell membrane. In active transport, molecules move up a concentration gradient.

Question 15

1-15. Which description accurately describes electrolytes?

a. Small lipid-soluble molecules
b. Large protein molecules
c. Micronutrients used to produce ATP
d. Electrically charged molecules

Answer 15

ANS: D
Electrolytes are electrically charged molecules. They are not lipid soluble, they are not made
up of protein, and they do not play a role in ATP production.

Question 16

1-16. A nurse is reading a chart and sees the term oncotic pressure. The nurse recalls that oncotic
pressure (colloid osmotic pressure) is determined by:
a. the concentration of sodium.
b. plasma proteins.
c. hydrostatic pressure.
d. the availability of membrane transporter proteins.

Answer 16

ANS: B
Oncotic pressure is determined by the effect of colloids or plasma proteins. The concentration
of sodium plays a role in tonicity. Hydrostatic pressure is the force within a vessel. Membrane
transporter proteins are involved in active transport within a concentration gradient.

Question 17

1-17. A patient has a body fluid of 300 mOsm/kg. This lab result is measuring:

a. osmolality.
b. osmolarity.
c. osmotic pressure.
d. oncotic pressure.

Answer 17

ANS: A
Osmolality measures the number of milliosmoles per kilogram of water, or the concentration
of molecules per weight of water, while osmolarity measures the number of milliosmoles per
liter of solution, or the concentration of molecules per volume of solution. Osmotic pressure is
the amount of hydrostatic pressure required to oppose the osmotic movement of water.
Oncotic pressure is from plasma proteins, not body fluids.

Question 18

1-18. A nurse is discussing the movement of fluid across the arterial end of capillary membranes
into the interstitial fluid surrounding the capillary. Which process of fluid movement is the
nurse describing?
a. Hydrostatic pressure
b. Osmosis
c. Diffusion
d. Active transport

Answer 18

ANS: A
Blood reaching the capillary bed has a hydrostatic pressure of 25–30 mm Hg, which is
sufficient force to push water across the thin capillary membranes into the interstitial space.
Osmosis involves the movement of fluid from an area of higher concentration to an area of
lower concentration. It does not involve pressure or force. Diffusion is the passive movement
of a solute from an area of higher solute concentration to an area of lower solute
concentration. Active transport involves movement up a concentration gradient.

Question 19

1-19. How are potassium and sodium transported across plasma membranes?

a. By passive electrolyte channels
b. By coupled channels
c. By adenosine triphosphate enzyme (ATPase)
d. By diffusion

Answer 19

ANS: C
The transporter protein ATPase is directly related to sodium and potassium transport via
active transport. Electrolyte movements require energy and do not move passively, nor are
they transported by diffusion. Enzymes, not electrolytes, are passed via coupled channels.

Question 20

1-20. The ion transporter that moves Na+ and Ca2+ simultaneously in the same direction is an
example of which of the following types of transport?
a. Biport
b. Uniport
c. Antiport
d. Symport

Answer 20

ANS: D
When ions are transported in one direction, it is termed symport. There is no such term as
biport. Uniport refers to the movement of a single molecule. Antiport refers to the movement
of molecules in the opposite direction.

Question 21

1-21. During which process are bacteria engulfed for ingestion?

a. Endocytosis
b. Pinocytosis
c. Phagocytosis
d. Exocytosis

Answer 21

ANS: C
Phagocytosis (cell eating) involves the ingestion of large particles, such as bacteria, through
the formation of large vesicles. Endocytosis involves the formation of vesicles to facilitate
movement into the cell. Pinocytosis is a type of endocytosis in which fluids and solute
molecules are ingested through the formation of small vesicles. Exocytosis occurs when
coated pits invaginate and internalize ligand-receptor complexes in coated vesicles.

Question 22

1-22. Some cancer drugs work during the cell cycle phase where nuclear and cytoplasmic divisions

occur. What is this cell cycle phase called?
a. G1
b. S
c. M
d. G2

Answer 22

ANS: C
The M phase includes both nuclear and cytoplasmic divisions. The G1 phase includes the
period between the M phase and the start of DNA synthesis. The S phase includes synthesis of
DNA in the cell nucleus. The G2 phase includes RNA and protein synthesis.

Question 23

1-23. Which causes the rapid change in the resting membrane potential that initiates an action
potential?
a. Potassium gates open, and potassium rushes into the cell, changing the membrane
potential from negative to positive.
b. Sodium gates open, and sodium rushes into the cell, changing the membrane
potential from negative to positive.
c. Sodium gates close, allowing potassium into the cell to change the membrane
potential from positive to negative.
d. Potassium gates close, allowing sodium into the cell to change the membrane
potential from positive to negative.

Answer 23

ANS: B
When the threshold is reached, the cell will continue to depolarize with no further stimulation.
The sodium gates open, and sodium rushes into the cell, causing the membrane potential to
reduce to zero and then become positive (depolarization). Sodium is involved in creating the
action potential, not potassium. The sodium gate and channel must be open, not closed. The
action potential is not affected by a change in the potassium gate.

Question 24

1-24. A cell is isolated, and electrophysiology studies reveal that the resting membrane potential is
–70 mV. The predominant intracellular ion is Na+, and the predominant extracellular ion is
K+. With voltage change, which of the following would result in an action potential?
a. K+ rushing into the cell
b. Na+ rushing into the cell
c. Na+ rushing out of the cell
d. K+ rushing out of the cell

Answer 24

ANS: A
With voltage change, potassium rushes into, not out of, the cell. Sodium movement is not
related to this process.

Question 25

1-25. A nurse teaching the staff about platelet-derived growth factor includes information that
platelet-derived growth factor (PDGF) stimulates the production of:

a. platelets.
b. epidermal cells.
c. connective tissue cells.
d. fibroblast cells.

Answer 25

ANS: C
Different types of cells require different growth factors; for example, PDGF stimulates the
production of connective tissue cells, but not platelets, epidermal cells, or fibroblast cells.

Question 26

1-26. The phase of the cell cycle during which the centromeres split and the sister chromatids are
pulled apart is referred to as:
a. anaphase.
b. telophase.
c. prophase.
d. metaphase.

Answer 26

ANS: A
Anaphase begins when the centromeres split and the sister chromatids are pulled apart. During
telophase, a new nuclear membrane is formed around each group of 46 chromosomes, the
spindle fibers disappear, and the chromosomes begin to uncoil. During prophase, the first
appearance of chromosomes occurs. Metaphase occurs when two centrioles located at
opposite poles of the cell pull the chromosomes to opposite sides of the cell.

Question 27

1-27. What is the role of cytokines in cell reproduction?

a. Provide growth factor for tissue growth and development.
b. Block progress of cell reproduction through the cell cycle.
c. Restrain cell growth and development.
d. Provide nutrients for cell growth and development.

Answer 27

ANS: A
Cytokines play a major role in the regulation of tissue growth and development but do not
restrain it. Cytokines help overcome intracellular braking mechanisms that restrain cell
growth and promote cell growth, but they do not provide nutrients.

Question 28

1-28. A student is reviewing functions of the cell. The student would be correct in identifying a
chief function of the nerve cell as:
a. sensory interpretation.
b. conductivity.
c. maintenance of homeostasis.
d. communication.

Answer 28

ANS: B
Conductivity, not sensory interpretation, homeostasis, or communication, is one of the eight
chief functions of nerve cells.

Question 29

1-1. A nurse recalls that the basic types of tissues are: (Select all that apply.)

a. nerve.
b. epithelial.
c. mucosal.
d. connective.
e. skeletal.
f. muscle.

Answer 29

ANS: A, B, D, F
The basic tissue types include nerve, epithelial, connective, and muscle. Mucosal is a type of
epithelial cell while skeletal is a type of connective tissue.

Question 30

1-2. Characteristics of prokaryotes include which of the following? (Select all that apply.)

a. They contain no organelles.
b. Their nuclear material is not encased by a nuclear membrane.
c. They contain a distinct nucleus.
d. They contain histones.
e. They contain a cellular membrane.

Answer 30

ANS: A, B
The prokaryotes lack a cellular membrane that encases nuclear material, thus they have no
distinct nucleus; organelles and histones are also missing.

Question 31

2-01. A nurse recalls the basic components of DNA are:

a. pentose sugars and four phosphate bases.
b. a phosphate molecule, deoxyribose, and four nitrogenous bases.
c. adenine, guanine, and purine.
d. codons, oxygen, and cytosine.

Answer 31

ANS: B
The three basic components of DNA are deoxyribose; a phosphate molecule; and four types of
nitrogenous, not phosphate, bases. DNA does not contain condone.

Question 32

2-02. Which of the following mutations have the most significant effect on protein synthesis?

a. Base pair substitutions
b. Silent mutations
c. Intron mutations
d. Frameshift mutations

Answer 32

ANS: D
The frameshift mutation involves the insertion or deletion of one or more base pairs of the
DNA molecule. This greatly alters the amino acid sequence, which affects protein synthesis.
The base pair substitution is a type of mutation in which one base pair replaces another. Silent
mutations do not change amino acids or protein synthesis. Intron mutations are part of RNA
sequencing.

Question 33

2-03. The base components of DNA are:

a. A, G, C, and U.
b. P, G, C, and T.
c. A, G, C, and T.
d. X, XX, XY, and YY.

Answer 33

ANS: C
The four base components of DNA are cytosine, thymine, adenine, and guanine, and are
commonly represented by their first letters (A, C, T, and G) and not components identified as
P or U. X, XX, XY, and YY are components of human chromosomes.

Question 34

2-04. A DNA strand has a region with the sequence ATCGGAT. Which of the following would be a
complementary strand?
a. CGATACGT
b. TAGCCTAG
c. TUGCCTUG
d. UAGCCUAG

Answer 34

ANS: B
The consistent pairing of adenine with thymine and of guanine with cytosine is known as
complementary base pairing; thus, A complements to T and C to G and vice versa throughout
the strand. A complements to T; thus, the first letter must be a T. U does not represent a
complement in the sequence.

Question 35

2-05. A biologist is explaining how RNA directs the synthesis of protein. Which process is the
biologist describing?
a. Termination
b. Transcription
c. Translocation
d. Translation

Answer 35

ANS: D
In translation, RNA directs the synthesis of a polypeptide, interacting with transfer RNA
(tRNA), a cloverleaf-shaped strand of about 80 nucleotides. Termination does not involve
synthesis of protein. Transcription is the process by which DNA specifies a sequence of
messenger RNA (mRNA). Translocation is the interchange of genetic material between
nonhomologous chromosomes.

Question 36

2-06. What is the result of homologous chromosomes failing to separate during meiosis?

a. Neurofibromatosis
b. Nondisjunction
c. Polyploidy
d. Conjoined twins

Answer 36

ANS: B
Nondisjunction is an error in which homologous chromosomes or sister chromatids fail to
separate normally during meiosis or mitosis. Neurofibromatosis is not due to chromosome
failure during meiosis. Polyploidy occurs when a euploid cell has more than the diploid
number of chromosomes. Conjoined twins are not due to chromosome failure during meiosis.

Question 37

2-07. A cell that does not contain a multiple of 23 chromosomes is called a _____ cell.

a. diploid
b. euploid
c. polyploid
d. haploid

Answer 37

ANS: C
A polyploid cell is one in which a euploid cell has more than 23 pairs of chromosomes. A
diploid cell is when the somatic cell nucleus has 46 chromosomes in 23 pairs. A euploid cell
is a cell with multiples of the normal number of chromosomes. A haploid cell has only one
member of each chromosome pair, for a total of 23 chromosomes.

Question 38

2-08. A 20-year-old pregnant female gives birth to a stillborn child. Autopsy reveals that the fetus
has 92 chromosomes. What term may be on the autopsy report to describe this condition?
a. Biploidy
b. Triploidy
c. Tetraploidy
d. Aneuploidy

Answer 38

ANS: C
Tetraploidy is a condition in which euploid cells have 92 chromosomes. Biploidy is a euploid
cell with two times more chromosomes, or 46. Triploidy is a zygote that has three copies of
each chromosome, rather than the usual two. Aneuploidy is when an aneuploid cell does not
contain a multiple of 23 chromosomes.

Question 39

2-09. The condition in which an extra portion of a chromosome is present in each cell is called:

a. reciprocal translocation.
b. partial trisomy.
c. inversion.
d. Down syndrome.

Answer 39

ANS: B
Partial trisomy is a condition in which only an extra portion of a chromosome is present in
each cell. A reciprocal translocation occurs when breaks take place in two different
chromosomes and the material is exchanged. An inversion occurs when two breaks take place
on a chromosome, followed by the reinsertion of the missing fragment at its original site, but
in inverted order. Down syndrome is an aneuploidy of the twenty-first chromosome.

Question 40

2-10. After a geneticist talks to a patient about being a chromosomal mosaic, the patient asks the
nurse what that means. How should the nurse respond? You may _____ genetic disease(s).
a. only be a carrier of the
b. have a mild form of the
c. have two
d. be sterile as a result of the

Answer 40

ANS: B
A chromosomal mosaic means the body has two or more different cell lines, each of which
has a different karyotype; thus, the person has a mild form of the disease. Mosaics are not
only carriers; they have the disease; they have two different lines but not two different
diseases; and they are not necessarily sterile.

Question 41

2-11. What is the most common cause of Down syndrome?

a. Paternal nondisjunction
b. Maternal translocations
c. Maternal nondisjunction
d. Paternal translocations

Answer 41

ANS: C
The most common cause of Down syndrome is maternal, not paternal, nondisjunction.
Translocation is not a cause of this syndrome.

Question 42

2-12. A patient wants to know the risk factors for Down syndrome. What is the nurse’s best
response?
a. Fetal exposure to mutagens in the uterus
b. Increased paternal age
c. Family history of Down syndrome
d. Pregnancy in women over age 35

Answer 42

ANS: D
The primary risk for Down syndrome is pregnancy in women over 35. Down syndrome is a
trisomy and not due to fetal exposure or paternal age. Down syndrome is a chromosomal
abnormality and is not related to family history.

Question 43

2-13. A 13-year-old girl has a karyotype that reveals an absent homologous X chromosome with
only a single X chromosome present. What medical diagnosis will the nurse observe on the
chart?
a. Down syndrome
b. Cri du chat syndrome
c. Turner syndrome
d. Fragile X syndrome

Answer 43

ANS: C
A condition with the presence of a single X chromosome and no homologous X or Y
chromosome, so the individual has a total of 45 chromosomes, is known as Turner syndrome.
Down syndrome is a change in one arm of a chromosome. Cri du chat syndrome is due to a
chromosome deletion. Fragile X syndrome is due to a break or a gap in a chromosome.

Question 44

2-14. What genetic disorder is the result if an individual possesses an XXY chromosome
configuration?
a. Turner
b. Klinefelter
c. Down
d. Fragile X

Answer 44

ANS: B
Individuals with at least two X chromosomes and one Y chromosome in each cell (47 XXY
karyotype) have a disorder known as Klinefelter syndrome. A condition with the presence of a
single X chromosome and no homologous X or Y chromosome, so the individual has a total
of 45 chromosomes, is known as Turner syndrome. Down syndrome is a trisomy. Fragile X
syndrome is due to a break or a gap in a chromosome, not an extra chromosome.

Question 45

2-15. A patient demonstrates severe mental retardation caused by a deletion of part of chromosome

5. What genetic disorder will the nurse see documented in the chart?
   a. Prader-Willi syndrome
   b. Down syndrome
   c. Cri du chat syndrome
   d. Trisomy X

Answer 45

ANS: C
Cri du chat syndrome means “cry of the cat” and describes the characteristic cry of the
affected child. Another symptom of the disorder is mental retardation. The disease is caused
by a deletion of part of the short arm of chromosome 5. Prader-Willi syndrome is
characterized by short stature, obesity, and hypogonadism. Down syndrome does cause
mental retardation but is due to chromosome 21, not chromosome 5. Trisomy X can result in
mental retardation but is due to an extra X chromosome.

Question 46

2-16. An aide asks the nurse why people who have neurofibromatosis will show varying degrees of
the disease. Which genetic principle should the nurse explain to the aide?
a. Penetrance
b. Expressivity
c. Dominance
d. Recessiveness

Answer 46

ANS: B
Expressivity is the extent of variation in phenotype associated with a particular genotype. For
neurofibromatosis, a variety of manifestations occur among individuals. The penetrance of a
trait is the percentage of individuals with a specific genotype who also exhibit the expected
phenotype. Dominance refers to observable traits and risk of transmission. Recessiveness
refers to silent strains with reduced risk of occurrence.

Question 47

2-17. Cystic fibrosis is caused by what gene abnormality?

a. X-linked dominant
b. X-linked recessive
c. Autosomal dominant
d. Autosomal recessive

Answer 47

ANS: D
Cystic fibrosis is an autosomal recessive disorder. It is not a result of X links or dominant
pathology.

Question 48

2-18. A 15-year-old female is diagnosed with Prader-Willi syndrome. This condition is an example
of:
a. genomic imprinting.
b. an autosomal recessive trait.
c. an autosomal dominant trait.
d. a sex-linked trait.

Answer 48

ANS: A
Prader-Willi, an example of gene imprinting, is not associated with any autosomal sex-linked
abnormality.

Question 49

2-19. A patient, age 9, is admitted to a pediatric unit with Duchenne muscular dystrophy. When
planning care, the nurse recalls the patient inherited this condition through a trait that is:
a. X-linked dominant.
b. X-influenced.
c. X-limited.
d. X-linked recessive.

Answer 49

ANS: D
Duchenne muscular dystrophy is a relatively common X-linked recessive, not dominant,
disorder. While it is sex linked, it is not X-limited or X-influenced.

Question 50

2-20. A child is diagnosed with cystic fibrosis. History reveals that the child’s parents are siblings.
Cystic fibrosis was most likely the result of:
a. X-inactivation.
b. genomic imprinting.
c. consanguinity.
d. obligate carriers.

Answer 50

ANS: C
Consanguinity refers to the mating of two related individuals, and the offspring of such
matings are said to be inbred. Consanguineous matings produce a significant increase in
recessive disorders and are seen most often in pedigrees for rare recessive disorders.
X-inactivation occurs when one X chromosome in the somatic cells of females is permanently
inactivated. Genomic imprinting is related to methylation and other changes. Obligate carriers
are those who have an affected parent and affected children and, therefore, must themselves
carry the mutation.

Question 51

2-21. A 12-year-old male is diagnosed with Klinefelter syndrome. His karyotype would reveal
which of the following?
a. XY
b. XX
c. XYY
d. XXY

Answer 51

ANS: D
A person with Klinefelter syndrome has an XXY karyotype. An XY is a normal male. An XX
is a normal female. An XYY is an aneuploid karyotype.

Question 52

2-22. To express a polygenic trait:

a. genes must interact with the environment.
b. several genes must act together.
c. multiple mutations must occur in the same family.
d. penetrance must occur.

Answer 52

ANS: B
Polygenic traits are those that result from several genes acting together. When environmental
factors influence the expression of the trait, the term multifactorial inheritance is used. When
multiple mutations occur in the same family, the mechanism most likely responsible is termed
germline mosaicism. Penetrance of a trait is the percentage of individuals with a specific
genotype who also exhibit the expected phenotype.

Question 53

2-23. What is the diagnosis of a 13-year-old female who has a karyotype that reveals an absent
homologous X chromosome with only a single X chromosome present? Her features include a
short stature, widely spaced nipples, and a reduced carrying angle at the elbow.
a. Down syndrome
b. Cri du chat syndrome
c. Turner syndrome
d. Klinefelter syndrome

Answer 53

ANS: C
Turner syndrome is characterized by short stature, female genitalia, webbed neck, shield-like
chest with underdeveloped breasts and widely spaced nipples, and imperfectly developed
ovaries. Down syndrome is characterized by distinctive characteristics: low nasal bridge,
epicanthal folds, protruding tongue, and low-set ears. Cri du chat syndrome is characterized
by low birth weight, severe mental retardation, microcephaly (smaller than normal head size),
and heart defects. Klinefelter syndrome is characterized by small testes, some development of
the breasts, sparse body hair, and long limbs.

Question 54

2-24. The gradual increase in height among the human population over the past 100 years is an
example of:
a. a polygenic trait.
b. a multifactorial trait.
c. crossing over.
d. recombination.

Answer 54

ANS: B
The gradual increase in height is an example of multifactorial traits influenced by genes and
also by environment. Polygenic traits result from several genes acting together. Crossing over
is an abnormal chromosome structure. Recombination results from new arrangements of
alleles.

Question 55

2-25. When discussing DNA replication, which enzyme is most important?

a. RNA polymerase
b. Transfer RNA
c. Messenger RNA
d. DNA polymerase

Answer 55

ANS: D
DNA polymerase, not RNA polymerase, is the primary enzyme involved in replication. It
adds bases to the new DNA strand and performs “proofreading” functions. Neither messenger
RNA nor transfer RNA is as important to DNA replication.

Question 56

2-26. The regions of the heterogeneous nuclear RNA that must be spliced out to form functional
RNA are called:
a. promoter sites.
b. introns.
c. exons.
d. anticodon.

Answer 56

ANS: B
When the mRNA is first transcribed from the DNA template, it reflects exactly the base
sequence of the DNA. In eukaryotes, many RNA sequences are removed by nuclear enzymes,
and the remaining sequences are spliced together to form the functional mRNA that migrates
to the cytoplasm. The excised sequences are called introns (intervening sequences), and the
sequences that are left to code for proteins are called exons. In translation, RNA directs the
synthesis of a polypeptide, a cloverleaf-shaped strand of about 80 nucleotides. The tRNA
molecule has a site where an amino acid attaches. The three-nucleotide sequence at the
opposite side of the cloverleaf is called the anticodon.

Question 57

2-27. A 50-year-old male was recently diagnosed with Huntington disease. Transmission of this
disease is associated with:
a. penetrance of a trait.
b. recurrence risk.
c. expressivity.
d. delayed age of onset.

Answer 57

ANS: D
A key feature of Huntington disease is its delayed age of onset such that symptoms are not
seen until 40 years of age or later. The penetrance of a trait is the percentage of individuals
with a specific genotype who also exhibit the expected phenotype. Recurrence risk is the
percentage of family members who will inherit the disease. Expressivity is the extent of
variation in phenotype associated with a particular genotype.

Question 58

2-28. What type of mutation does not change the amino acid sequence and thus has no observable
consequence?
a. Frameshift
b. Spontaneous
c. Silent
d. Missense

Answer 58

ANS: C
Silent mutations do not change the amino acid sequence and therefore have no consequences.
Frameshift mutations involve the insertion or deletion of one or more base pairs of the DNA
molecule. They alter the amino acid sequence. Spontaneous mutations occur in the absence of
exposure to a mutagen and produce changes in the amino acid sequence. Missense mutations,
a form of base pair substitution, alter amino acids, which produce a change (i.e., the “sense”)
in a single amino acid.

Question 59

2-29. A nurse is reviewing the pedigree chart. When checking for a proband, what is the nurse
looking for?
a. The person who is first diagnosed with a genetic disease.
b. The individual who has a disease gene but is phenotypically normal.
c. The phenotype of genetic material.
d. The codominance.

Answer 59

ANS: A
The pedigree chart summarizes family relationships and shows which members of a family
are affected by a genetic disease. The pedigree begins with the proband. The person who has a
disease gene but is phenotypically normal is a carrier. The phenotype is the result of both
genotype and environment; it is not a proband. Codominance is not represented by a proband,
but it occurs when the heterozygote is distinguishable from both homozygotes.

Question 60

2-30. Which of the following disorders is manifested primarily in males?

a. Cystic fibrosis
b. Neurofibromatosis
c. Muscular dystrophy
d. Klinefelter syndrome

Answer 60

ANS: C
Muscular dystrophy is manifested primarily in males. Cystic fibrosis, neurofibromatosis, and
Klinefelter syndrome are manifested in both males and females.

Question 61

2-1. When the nurse is teaching the staff about X-linked recessive disorders, which information
should the nurse include? (Select all that apply.)
a. The trait is seen much more often in females than in males.
b. The trait is never transmitted from father to son.
c. The gene can be transmitted through a series of carrier females.
d. The gene is passed from an affected father to all his daughters.
e. The trait never skips generations.

Answer 61

ANS: B, C, D
The principles of X-linked recessive inheritance include: the trait is seen much more often in
males than in females; the trait is never transmitted from father to son; the gene can be
transmitted through a series of carrier females; the gene is passed from an affected father to all
his daughters, who, as phenotypically normal carriers, transmit it to approximately half their
sons, who are affected. X-linked recessive disorders can skip generations since it is a one in
four chance.