McCance & Huether’s Pathophysiology
The Biologic Basis for Disease in Adults and Children
9th Edition
• Author(s)Julia Rogers
TEST BANK
McCance & Huether — Pathophysiology, 9th Ed. — Chapter 1:
Cellular Biology.
Chapter 1, Cellular Communication and Signal Transduction
A patient with a chronic inflammatory condition is prescribed a
new medication that acts by binding to intracellular receptors
and directly influencing gene transcription. Which of the
following chemical messengers most likely utilizes this same
mechanism of action for its physiological effects?
A) Insulin
B) Thyroxine
C) Epinephrine
D) Acetylcholine
Correct Answer: B
Rationale: Thyroxine is a lipid-soluble hormone derived from
,tyrosine. Because it is lipid-soluble, it can diffuse directly across
the plasma membrane and bind to intracellular receptors in the
nucleus, forming a complex that acts as a transcription factor to
alter gene expression. Insulin, epinephrine, and acetylcholine
are water-soluble first messengers that bind to surface
membrane receptors and initiate intracellular signaling
cascades (e.g., kinase activation or second messenger systems)
because they cannot cross the hydrophobic lipid bilayer.
Teaching Point: Lipid-soluble hormones (steroids, thyroid
hormones) act via intracellular receptors and direct gene
regulation.
2.
Chapter 1, Cellular Metabolism
A researcher is studying a cell line with a genetic defect that
renders the enzyme pyruvate dehydrogenase completely
nonfunctional. Which of the following would be the most direct
consequence of this defect under aerobic conditions?
A) Inability to initiate glycolysis
B) Accumulation of acetyl-CoA in the mitochondrial matrix
C) Failure to convert pyruvate to acetyl-CoA
D) Increased production of NAD+ in the cytoplasm
Correct Answer: C
Rationale: Pyruvate dehydrogenase is the mitochondrial
enzyme complex that catalyzes the conversion of pyruvate into
acetyl-CoA, which then enters the citric acid cycle. A
nonfunctional enzyme would directly cause a failure in this
critical step. Glycolysis (A) can still occur, producing pyruvate.
,Acetyl-CoA (B) would not accumulate as it cannot be formed.
NAD+ regeneration (D) occurs in the mitochondria via the
electron transport chain, which is stalled due to lack of acetyl-
CoA.
Teaching Point: Pyruvate dehydrogenase is the crucial link
between anaerobic glycolysis and the aerobic citric acid cycle.
3.
Chapter 1, Structure and Function of Cellular Components
A patient presents with a rare genetic disorder characterized by
severe weakness and fatigue. A muscle biopsy reveals
abnormally shaped nuclei and disorganization of cytoplasmic
organelles. Which cellular structure is most likely primarily
defective in this condition?
A) Golgi apparatus
B) Endoplasmic reticulum
C) Cytoskeleton
D) Lysosome
Correct Answer: C
Rationale: The cytoskeleton is a network of protein filaments
(microtubules, microfilaments, intermediate filaments) that
maintains cellular shape, organizes cytoplasmic contents, and
facilitates intracellular transport and organelle positioning.
Defects in cytoskeletal components (e.g., certain muscular
dystrophies) lead to disorganization of organelles and structural
weakness. The other organelles are important for processing
(Golgi, ER) or degradation (lysosome) but are not the primary
structures responsible for overall cellular architecture and
, organelle placement.
Teaching Point: The cytoskeleton provides structural support,
organizes organelles, and enables cell motility.
4.
Chapter 1, Membrane Transport: Cellular Intake and Output
In the intestinal epithelium, glucose is moved from the
intestinal lumen into the epithelial cell against its concentration
gradient by coupling its transport with the simultaneous
movement of sodium ions down their concentration gradient.
This process is best described as:
A) Simple diffusion
B) Facilitated diffusion
C) Primary active transport
D) Secondary active transport
Correct Answer: D
Rationale: Secondary active transport uses the energy stored in
an ion concentration gradient (in this case, sodium) to move
another substance (glucose) against its gradient. The sodium
gradient is established and maintained by the Na+/K+ ATPase
pump, which is a primary active transport system (uses ATP
directly). Simple diffusion (A) is passive and does not require a
carrier. Facilitated diffusion (B) uses a carrier but moves
substances down their gradient without energy coupling.
Primary active transport (C) directly hydrolyzes ATP.
Teaching Point: Secondary active transport harnesses the
energy of one ion's gradient to power the movement of another
molecule.
The Biologic Basis for Disease in Adults and Children
9th Edition
• Author(s)Julia Rogers
TEST BANK
McCance & Huether — Pathophysiology, 9th Ed. — Chapter 1:
Cellular Biology.
Chapter 1, Cellular Communication and Signal Transduction
A patient with a chronic inflammatory condition is prescribed a
new medication that acts by binding to intracellular receptors
and directly influencing gene transcription. Which of the
following chemical messengers most likely utilizes this same
mechanism of action for its physiological effects?
A) Insulin
B) Thyroxine
C) Epinephrine
D) Acetylcholine
Correct Answer: B
Rationale: Thyroxine is a lipid-soluble hormone derived from
,tyrosine. Because it is lipid-soluble, it can diffuse directly across
the plasma membrane and bind to intracellular receptors in the
nucleus, forming a complex that acts as a transcription factor to
alter gene expression. Insulin, epinephrine, and acetylcholine
are water-soluble first messengers that bind to surface
membrane receptors and initiate intracellular signaling
cascades (e.g., kinase activation or second messenger systems)
because they cannot cross the hydrophobic lipid bilayer.
Teaching Point: Lipid-soluble hormones (steroids, thyroid
hormones) act via intracellular receptors and direct gene
regulation.
2.
Chapter 1, Cellular Metabolism
A researcher is studying a cell line with a genetic defect that
renders the enzyme pyruvate dehydrogenase completely
nonfunctional. Which of the following would be the most direct
consequence of this defect under aerobic conditions?
A) Inability to initiate glycolysis
B) Accumulation of acetyl-CoA in the mitochondrial matrix
C) Failure to convert pyruvate to acetyl-CoA
D) Increased production of NAD+ in the cytoplasm
Correct Answer: C
Rationale: Pyruvate dehydrogenase is the mitochondrial
enzyme complex that catalyzes the conversion of pyruvate into
acetyl-CoA, which then enters the citric acid cycle. A
nonfunctional enzyme would directly cause a failure in this
critical step. Glycolysis (A) can still occur, producing pyruvate.
,Acetyl-CoA (B) would not accumulate as it cannot be formed.
NAD+ regeneration (D) occurs in the mitochondria via the
electron transport chain, which is stalled due to lack of acetyl-
CoA.
Teaching Point: Pyruvate dehydrogenase is the crucial link
between anaerobic glycolysis and the aerobic citric acid cycle.
3.
Chapter 1, Structure and Function of Cellular Components
A patient presents with a rare genetic disorder characterized by
severe weakness and fatigue. A muscle biopsy reveals
abnormally shaped nuclei and disorganization of cytoplasmic
organelles. Which cellular structure is most likely primarily
defective in this condition?
A) Golgi apparatus
B) Endoplasmic reticulum
C) Cytoskeleton
D) Lysosome
Correct Answer: C
Rationale: The cytoskeleton is a network of protein filaments
(microtubules, microfilaments, intermediate filaments) that
maintains cellular shape, organizes cytoplasmic contents, and
facilitates intracellular transport and organelle positioning.
Defects in cytoskeletal components (e.g., certain muscular
dystrophies) lead to disorganization of organelles and structural
weakness. The other organelles are important for processing
(Golgi, ER) or degradation (lysosome) but are not the primary
structures responsible for overall cellular architecture and
, organelle placement.
Teaching Point: The cytoskeleton provides structural support,
organizes organelles, and enables cell motility.
4.
Chapter 1, Membrane Transport: Cellular Intake and Output
In the intestinal epithelium, glucose is moved from the
intestinal lumen into the epithelial cell against its concentration
gradient by coupling its transport with the simultaneous
movement of sodium ions down their concentration gradient.
This process is best described as:
A) Simple diffusion
B) Facilitated diffusion
C) Primary active transport
D) Secondary active transport
Correct Answer: D
Rationale: Secondary active transport uses the energy stored in
an ion concentration gradient (in this case, sodium) to move
another substance (glucose) against its gradient. The sodium
gradient is established and maintained by the Na+/K+ ATPase
pump, which is a primary active transport system (uses ATP
directly). Simple diffusion (A) is passive and does not require a
carrier. Facilitated diffusion (B) uses a carrier but moves
substances down their gradient without energy coupling.
Primary active transport (C) directly hydrolyzes ATP.
Teaching Point: Secondary active transport harnesses the
energy of one ion's gradient to power the movement of another
molecule.
