Robbins & Cotran 10th Ed. Pathology Test Bank | Chapter-
by-Chapter Questions & Verified Solutions
Robbins & Cotran Pathologic Basis of Disease
10th Edition
• Author(s)Vinay Kumar; Abul K. Abbas; Jon C. Aster
Pathology MCQ Bank: Cellular Basis of Health and Disease
1. Chapter 1: Cellular Metabolism and Mitochondrial Function
A 2-month-old male infant is brought to the emergency
department with severe lethargy and lactic acidosis. Imaging
reveals bilateral lesions in the basal ganglia. A muscle biopsy
shows abnormal, ragged red fibers. This constellation of
findings most directly points to a pathologic defect in which of
the following fundamental cellular processes?
A. Receptor-mediated endocytosis
B. Oxidative phosphorylation
C. Glycogenolysis
D. Apoptosis execution
Correct Answer: B. Oxidative phosphorylation
Rationale: The clinical presentation (lactic acidosis, basal
ganglia lesions, ragged red fibers) is characteristic of a
,mitochondrial encephalomyopathy, such as Leigh syndrome.
These disorders are caused by defects in the mitochondrial
electron transport chain, which is responsible for oxidative
phosphorylation. This disrupts ATP production, particularly in
high-energy-demand tissues like the nervous system and
muscle .
• Incorrect A: Receptor-mediated endocytosis is involved in
nutrient uptake (e.g., LDL cholesterol) and is not primarily
related to energy production or this symptom complex.
• Incorrect C: While glycogenolysis can contribute to energy
availability, its impairment does not cause the specific
neurologic and histologic findings described.
• Incorrect D: Apoptosis is a regulated cell death process; its
failure is linked to hyperproliferative disorders like cancer,
not acute metabolic crises.
Teaching Point: Defects in mitochondrial oxidative
phosphorylation cause severe energy deficits in highly
metabolic tissues like brain and muscle.
2. Chapter 1: The Genome
A researcher is studying a disease caused by a mutation in a
gene encoding a structural protein. The mutation is present in
all cells of an affected individual but the disease phenotype only
manifests in the skin. This best illustrates the concept of:
A. Incomplete penetrance
B. Somatic mutation
,C. Cellular mosaicism
D. Cell-type-specific expression
Correct Answer: D. Cell-type-specific expression
Rationale: The fact that the germline mutation is present in all
cells but the pathology is restricted to the skin indicates that
the gene is only expressed and critical for function in that
specific cell type. This is a key principle in genetics and
pathology, where the same genetic mutation can have tissue-
specific effects based on which cells actually use the protein .
• Incorrect A: Incomplete penetrance means not all
individuals with the mutation show the disease, but this
scenario describes a single individual with tissue-specific
effects.
• Incorrect B: A somatic mutation would not be present in all
cells of the body.
• Incorrect C: Cellular mosaicism implies that only a subset
of cells in a tissue carry the mutation, which contradicts
the "present in all cells" statement.
Teaching Point: Gene expression patterns determine the
tissue-specific manifestations of genetic diseases.
3. Chapter 1: Cellular Housekeeping
A patient with a rare neurodegenerative disorder has an
accumulation of damaged organelles and protein aggregates
within neurons. Genetic analysis reveals a mutation in a gene
critical for the initial stages of autophagy, preventing the
, formation of autophagosomes. This defect most directly
impairs:
A. Ubiquitin-proteasome degradation
B. Phagocytosis of extracellular debris
C. Delivery of cytoplasmic cargo to lysosomes
D. Peroxisomal fatty acid oxidation
Correct Answer: C. Delivery of cytoplasmic cargo to lysosomes
Rationale: Autophagy is the primary cellular mechanism for
degrading and recycling damaged organelles and long-lived
proteins. The process begins with the formation of a double-
membrane structure (phagophore) that engulfs cytoplasmic
cargo to form an autophagosome, which then fuses with a
lysosome for degradation. A defect at this initial stage would
prevent this essential housekeeping function .
• Incorrect A: The ubiquitin-proteasome system primarily
degrades short-lived and misfolded proteins, not entire
organelles.
• Incorrect B: Phagocytosis is a specialized function of
certain white blood cells for engulfing external particles,
not an intracellular housekeeping process in neurons.
• Incorrect D: Peroxisomes are involved in beta-oxidation of
fatty acids and reactive oxygen species metabolism, not
bulk degradation of organelles.
Teaching Point: Autophagy is a vital quality control process
that clears damaged organelles and protein aggregates
from cells.
by-Chapter Questions & Verified Solutions
Robbins & Cotran Pathologic Basis of Disease
10th Edition
• Author(s)Vinay Kumar; Abul K. Abbas; Jon C. Aster
Pathology MCQ Bank: Cellular Basis of Health and Disease
1. Chapter 1: Cellular Metabolism and Mitochondrial Function
A 2-month-old male infant is brought to the emergency
department with severe lethargy and lactic acidosis. Imaging
reveals bilateral lesions in the basal ganglia. A muscle biopsy
shows abnormal, ragged red fibers. This constellation of
findings most directly points to a pathologic defect in which of
the following fundamental cellular processes?
A. Receptor-mediated endocytosis
B. Oxidative phosphorylation
C. Glycogenolysis
D. Apoptosis execution
Correct Answer: B. Oxidative phosphorylation
Rationale: The clinical presentation (lactic acidosis, basal
ganglia lesions, ragged red fibers) is characteristic of a
,mitochondrial encephalomyopathy, such as Leigh syndrome.
These disorders are caused by defects in the mitochondrial
electron transport chain, which is responsible for oxidative
phosphorylation. This disrupts ATP production, particularly in
high-energy-demand tissues like the nervous system and
muscle .
• Incorrect A: Receptor-mediated endocytosis is involved in
nutrient uptake (e.g., LDL cholesterol) and is not primarily
related to energy production or this symptom complex.
• Incorrect C: While glycogenolysis can contribute to energy
availability, its impairment does not cause the specific
neurologic and histologic findings described.
• Incorrect D: Apoptosis is a regulated cell death process; its
failure is linked to hyperproliferative disorders like cancer,
not acute metabolic crises.
Teaching Point: Defects in mitochondrial oxidative
phosphorylation cause severe energy deficits in highly
metabolic tissues like brain and muscle.
2. Chapter 1: The Genome
A researcher is studying a disease caused by a mutation in a
gene encoding a structural protein. The mutation is present in
all cells of an affected individual but the disease phenotype only
manifests in the skin. This best illustrates the concept of:
A. Incomplete penetrance
B. Somatic mutation
,C. Cellular mosaicism
D. Cell-type-specific expression
Correct Answer: D. Cell-type-specific expression
Rationale: The fact that the germline mutation is present in all
cells but the pathology is restricted to the skin indicates that
the gene is only expressed and critical for function in that
specific cell type. This is a key principle in genetics and
pathology, where the same genetic mutation can have tissue-
specific effects based on which cells actually use the protein .
• Incorrect A: Incomplete penetrance means not all
individuals with the mutation show the disease, but this
scenario describes a single individual with tissue-specific
effects.
• Incorrect B: A somatic mutation would not be present in all
cells of the body.
• Incorrect C: Cellular mosaicism implies that only a subset
of cells in a tissue carry the mutation, which contradicts
the "present in all cells" statement.
Teaching Point: Gene expression patterns determine the
tissue-specific manifestations of genetic diseases.
3. Chapter 1: Cellular Housekeeping
A patient with a rare neurodegenerative disorder has an
accumulation of damaged organelles and protein aggregates
within neurons. Genetic analysis reveals a mutation in a gene
critical for the initial stages of autophagy, preventing the
, formation of autophagosomes. This defect most directly
impairs:
A. Ubiquitin-proteasome degradation
B. Phagocytosis of extracellular debris
C. Delivery of cytoplasmic cargo to lysosomes
D. Peroxisomal fatty acid oxidation
Correct Answer: C. Delivery of cytoplasmic cargo to lysosomes
Rationale: Autophagy is the primary cellular mechanism for
degrading and recycling damaged organelles and long-lived
proteins. The process begins with the formation of a double-
membrane structure (phagophore) that engulfs cytoplasmic
cargo to form an autophagosome, which then fuses with a
lysosome for degradation. A defect at this initial stage would
prevent this essential housekeeping function .
• Incorrect A: The ubiquitin-proteasome system primarily
degrades short-lived and misfolded proteins, not entire
organelles.
• Incorrect B: Phagocytosis is a specialized function of
certain white blood cells for engulfing external particles,
not an intracellular housekeeping process in neurons.
• Incorrect D: Peroxisomes are involved in beta-oxidation of
fatty acids and reactive oxygen species metabolism, not
bulk degradation of organelles.
Teaching Point: Autophagy is a vital quality control process
that clears damaged organelles and protein aggregates
from cells.
