APEA Pathophysiology EXAM Questions
and Ansẉers with
Rationale 2026\2027 update
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Questions and Ansẉers
format set of multiple-choice
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,───────────────────────────────────────────────────────
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Which of the following cellular adaptations is characterized by an increase in
the number of cells in an organ or tissue?
A. Hypertrophy
B. Hyperplasia
C. Atrophy
D. Metaplasia
Answer: B
Rationale: Hyperplasia is an increase in the number of cells in an organ or
tissue, often occurring in response to hormonal stimulation or chronic injury.
Hypertrophy is an increase in cell size. Atrophy is a decrease in cell size.
Metaplasia is the replacement of one adult cell type with another.
A patient presents with a painless, hard, fixed mass in the breast. Biopsy
reveals malignant cells. Which cellular alteration is most indicative of
malignancy?
A. Anaplasia
B. Hyperplasia
C. Dysplasia
D. Metaplasia
Answer: A
Rationale: Anaplasia refers to cells that are undifferentiated, have variable
nuclear shapes and sizes, and lack normal organization, which is a hallmark of
malignancy. Hyperplasia, dysplasia, and metaplasia are generally reversible or
premalignant changes but do not definitively indicate cancer like anaplasia
does.
What is the primary intracellular molecule that binds to oxygen and delivers it
to the mitochondria for oxidative phosphorylation?
A. Cytochrome c
B. Myoglobin
C. Hemoglobin
D. Ribosomes
Answer: A
Rationale: Cytochrome c is a vital component of the electron transport chain in
the mitochondria, acting as an electron carrier. While hemoglobin carries
oxygen in the blood and myoglobin stores it in muscle, cytochrome c is the
,intracellular molecule that directly interacts with oxygen in the mitochondria to
produce ATP.
Which of the following is a reversible cellular injury characterized by the
accumulation of triglycerides within the cytoplasm?
A. Cellular atrophy
B. Fatty change (steatosis)
C. Coagulative necrosis
D. Apoptosis
Answer: B
Rationale: Fatty change, or steatosis, is a reversible form of cellular injury often
seen in the liver due to alcohol abuse, diabetes, or obesity, where triglycerides
accumulate in the cytoplasm. Coagulative necrosis and apoptosis are forms of
cell death, not reversible injury.
A patient with severe ischemia to the heart muscle experiences cell death. The
necrotic cells maintain their cellular outlines but lose their nuclei. What type of
necrosis is this?
A. Liquefactive necrosis
B. Caseous necrosis
C. Coagulative necrosis
D. Fat necrosis
Answer: C
Rationale: Coagulative necrosis is most commonly caused by ischemia (lack of
blood flow) in solid organs like the heart and kidneys. The architecture of the
dead tissue is preserved for a few days, but the nuclei disappear. Liquefactive
necrosis turns tissue into a liquid mass, typical of brain infarcts. Caseous
necrosis is seen in tuberculosis.
What is the primary mechanism by which free radicals cause cellular injury?
A. Directly altering DNA sequences
B. Lipid peroxidation of cell membranes
C. Inhibiting ribosome function
D. Activating apoptosis via the intrinsic pathway
Answer: B
Rationale: Free radicals are highly unstable molecules with an unpaired
electron. They cause cellular injury primarily by stealing electrons from cell
membrane lipids, a process called lipid peroxidation. This damages the cell
membrane, increases permeability, and eventually leads to cell death.
Which of the following enzymes is considered a highly specific marker for acute
myocardial infarction (AMI)?
A. Creatine kinase-MB (CK-MB)
B. Lactate dehydrogenase (LDH)
, C. Troponin I and T
D. Aspartate aminotransferase (AST)
Answer: C
Rationale: Cardiac troponins (I and T) are regulatory proteins found strictly in
cardiac muscle. They are highly specific and sensitive markers for myocardial
injury and are the preferred biomarkers for diagnosing an AMI. CK-MB is also
used but is less specific than troponin.
A patient has a genetic deficiency in alpha-1-antitrypsin. What is the expected
pathophysiological consequence?
A. Progressive liver cirrhosis
B. Pancreatic exocrine insufficiency
C. Early-onset emphysema
D. Chronic kidney disease
Answer: C
Rationale: Alpha-1-antitrypsin inhibits proteolytic enzymes, particularly
neutrophil elastase in the lungs. A deficiency allows unopposed destruction of
alveolar walls by elastase, leading to panacinar emphysema, especially in the
lower lobes, at a young age.
Which type of hypersensitivity reaction is mediated by IgE antibodies bound to
mast cells and basophils?
A. Type I
B. Type II
C. Type III
D. Type IV
Answer: A
Rationale: Type I hypersensitivity (immediate) is mediated by IgE. Upon
exposure to an allergen, IgE cross-links on mast cells, causing degranulation
and the release of histamine, heparin, and other inflammatory mediators. Type
II is antibody-mediated cytotoxic, Type III is immune complex-mediated, and
Type IV is T-cell mediated (delayed).
A patient develops a transfusion reaction due to ABO incompatibility. Which
hypersensitivity reaction is this classified as?
A. Type I
B. Type II
C. Type III
D. Type IV
Answer: B
Rationale: Type II hypersensitivity reactions involve IgG or IgM antibodies
binding to antigens on cell surfaces, leading to complement activation,
and Ansẉers with
Rationale 2026\2027 update
This Exam contains:
Guarantee passing score
Questions and Ansẉers
format set of multiple-choice
Expert-Verified Explanation
Verified ẉith trusted textbooks
,───────────────────────────────────────────────────────
─
Which of the following cellular adaptations is characterized by an increase in
the number of cells in an organ or tissue?
A. Hypertrophy
B. Hyperplasia
C. Atrophy
D. Metaplasia
Answer: B
Rationale: Hyperplasia is an increase in the number of cells in an organ or
tissue, often occurring in response to hormonal stimulation or chronic injury.
Hypertrophy is an increase in cell size. Atrophy is a decrease in cell size.
Metaplasia is the replacement of one adult cell type with another.
A patient presents with a painless, hard, fixed mass in the breast. Biopsy
reveals malignant cells. Which cellular alteration is most indicative of
malignancy?
A. Anaplasia
B. Hyperplasia
C. Dysplasia
D. Metaplasia
Answer: A
Rationale: Anaplasia refers to cells that are undifferentiated, have variable
nuclear shapes and sizes, and lack normal organization, which is a hallmark of
malignancy. Hyperplasia, dysplasia, and metaplasia are generally reversible or
premalignant changes but do not definitively indicate cancer like anaplasia
does.
What is the primary intracellular molecule that binds to oxygen and delivers it
to the mitochondria for oxidative phosphorylation?
A. Cytochrome c
B. Myoglobin
C. Hemoglobin
D. Ribosomes
Answer: A
Rationale: Cytochrome c is a vital component of the electron transport chain in
the mitochondria, acting as an electron carrier. While hemoglobin carries
oxygen in the blood and myoglobin stores it in muscle, cytochrome c is the
,intracellular molecule that directly interacts with oxygen in the mitochondria to
produce ATP.
Which of the following is a reversible cellular injury characterized by the
accumulation of triglycerides within the cytoplasm?
A. Cellular atrophy
B. Fatty change (steatosis)
C. Coagulative necrosis
D. Apoptosis
Answer: B
Rationale: Fatty change, or steatosis, is a reversible form of cellular injury often
seen in the liver due to alcohol abuse, diabetes, or obesity, where triglycerides
accumulate in the cytoplasm. Coagulative necrosis and apoptosis are forms of
cell death, not reversible injury.
A patient with severe ischemia to the heart muscle experiences cell death. The
necrotic cells maintain their cellular outlines but lose their nuclei. What type of
necrosis is this?
A. Liquefactive necrosis
B. Caseous necrosis
C. Coagulative necrosis
D. Fat necrosis
Answer: C
Rationale: Coagulative necrosis is most commonly caused by ischemia (lack of
blood flow) in solid organs like the heart and kidneys. The architecture of the
dead tissue is preserved for a few days, but the nuclei disappear. Liquefactive
necrosis turns tissue into a liquid mass, typical of brain infarcts. Caseous
necrosis is seen in tuberculosis.
What is the primary mechanism by which free radicals cause cellular injury?
A. Directly altering DNA sequences
B. Lipid peroxidation of cell membranes
C. Inhibiting ribosome function
D. Activating apoptosis via the intrinsic pathway
Answer: B
Rationale: Free radicals are highly unstable molecules with an unpaired
electron. They cause cellular injury primarily by stealing electrons from cell
membrane lipids, a process called lipid peroxidation. This damages the cell
membrane, increases permeability, and eventually leads to cell death.
Which of the following enzymes is considered a highly specific marker for acute
myocardial infarction (AMI)?
A. Creatine kinase-MB (CK-MB)
B. Lactate dehydrogenase (LDH)
, C. Troponin I and T
D. Aspartate aminotransferase (AST)
Answer: C
Rationale: Cardiac troponins (I and T) are regulatory proteins found strictly in
cardiac muscle. They are highly specific and sensitive markers for myocardial
injury and are the preferred biomarkers for diagnosing an AMI. CK-MB is also
used but is less specific than troponin.
A patient has a genetic deficiency in alpha-1-antitrypsin. What is the expected
pathophysiological consequence?
A. Progressive liver cirrhosis
B. Pancreatic exocrine insufficiency
C. Early-onset emphysema
D. Chronic kidney disease
Answer: C
Rationale: Alpha-1-antitrypsin inhibits proteolytic enzymes, particularly
neutrophil elastase in the lungs. A deficiency allows unopposed destruction of
alveolar walls by elastase, leading to panacinar emphysema, especially in the
lower lobes, at a young age.
Which type of hypersensitivity reaction is mediated by IgE antibodies bound to
mast cells and basophils?
A. Type I
B. Type II
C. Type III
D. Type IV
Answer: A
Rationale: Type I hypersensitivity (immediate) is mediated by IgE. Upon
exposure to an allergen, IgE cross-links on mast cells, causing degranulation
and the release of histamine, heparin, and other inflammatory mediators. Type
II is antibody-mediated cytotoxic, Type III is immune complex-mediated, and
Type IV is T-cell mediated (delayed).
A patient develops a transfusion reaction due to ABO incompatibility. Which
hypersensitivity reaction is this classified as?
A. Type I
B. Type II
C. Type III
D. Type IV
Answer: B
Rationale: Type II hypersensitivity reactions involve IgG or IgM antibodies
binding to antigens on cell surfaces, leading to complement activation,
