NR 507 WEEK 4 MIDTERM EXAM QUESTIONS
1-150 NR-507 ADVANCED PATHOPHYSIOLOGY
NR 507 WEEK 4 MIDTERM EXAM REVISED
ONLINE PROCTORED QUESTIONS AND
ANSWERS 100% GUARANTEED PASS..
1. A researcher is studying a signaling pathway in which a ligand binds to a receptor tyrosine
kinase (RTK), leading to activation of Ras and subsequent phosphorylation of ERK. Which of the
following mutations would most likely result in constitutive activation of this pathway independent
of ligand binding?
A. A gain-of-function mutation in the phosphatase that dephosphorylates ERK
B. A loss-of-function mutation in the GTPase-activating protein (GAP) for Ras
C. A loss-of-function mutation in the adaptor protein Grb2
D. A gain-of-function mutation in the guanine nucleotide exchange factor (GEF) for Ras
Answer: B
Rationale: A loss-of-function mutation in the GAP for Ras would impair the conversion of active
Ras-GTP to inactive Ras-GDP, leading to prolonged Ras signaling and constitutive pathway activation.
Option A would enhance ERK activity but is downstream. Option C would reduce signaling. Option D
could activate Ras but requires ligand binding to recruit GEF; a GEF gain-of-function mutation alone
may not cause constitutive activation without receptor activation.
2. A 45-year-old individual with a history of metabolic syndrome presents with acute chest pain.
Laboratory findings show elevated cardiac troponin I and a serum C-reactive protein (CRP) level
of 15 mg/L (normal <3 mg/L). Which of the following best describes the pathophysiological
sequence leading to the acute coronary event?
A. Endothelial dysfunction !’ decreased nitric oxide !’ platelet aggregation !’ thrombus formation
B. Macrophage foam cell apoptosis !’ lipid core expansion !’ plaque erosion !’ distal embolization
C. Plaque rupture !’ exposure of subendothelial collagen !’ platelet adhesion and activation !’ thrombus formation
D. Smooth muscle cell proliferation !’ intimal hyperplasia !’ critical stenosis !’ demand ischemia
Answer: C
Rationale: Acute coronary syndrome typically results from plaque rupture, exposing highly thrombogenic
subendothelial collagen, leading to platelet adhesion, activation, and thrombus formation. Elevated CRP
indicates systemic inflammation contributing to plaque instability. Option A describes early endothelial
dysfunction. Option B describes a mechanism for embolism from a lipid core but not the primary event.
Option D describes stable atherosclerosis and demand ischemia, not acute coronary syndrome.
Page 1
,3. Which of the following mechanisms best explains the development of hypocalcemia in a patient
with acute pancreatitis?
A. Increased renal excretion of calcium due to tubular damage
B. Sequestration of calcium in the form of calcium soaps in necrotic fat
C. Impaired intestinal absorption of calcium due to pancreatic enzyme deficiency
D. Increased calcitonin secretion from the thyroid in response to inflammation
Answer: B
Rationale: In acute pancreatitis, pancreatic enzymes (lipase) released into the peritoneum hydrolyze
triglycerides into free fatty acids, which then chelate calcium to form calcium soaps (saponification) in
necrotic adipose tissue, leading to hypocalcemia. Option A is not a primary mechanism. Option C
occurs in chronic pancreatitis. Option D is not a significant mechanism; calcitonin has a minor role in
calcium regulation.
4. A patient with a history of recurrent thromboembolism is found to have a prolonged activated
partial thromboplastin time (aPTT) that does not correct with mixing with normal plasma. Which
of the following is the most likely cause?
A. Factor VIII deficiency (hemophilia A)
B. Vitamin K deficiency
C. Lupus anticoagulant
D. Warfarin therapy
Answer: C
Rationale: Lupus anticoagulant is an antiphospholipid antibody that interferes with
phospholipid-dependent coagulation tests, causing a prolonged aPTT that does not correct with mixing
due to the presence of an inhibitor. Despite the in vitro prolongation, lupus anticoagulant is associated
with a prothrombotic state. Factor VIII deficiency would correct with mixing. Vitamin K deficiency and
warfarin affect the PT more than aPTT and correct with mixing.
5. A researcher is investigating a tumor suppressor gene that undergoes loss of heterozygosity
(LOH) in many cancers. The gene encodes a protein that inhibits cyclin-dependent kinases (CDKs)
and is involved in the G1/S checkpoint. Which of the following genes is most likely being studied?
A. TP53
B. RB1
C. PTEN
D. APC
Answer: B
Rationale: RB1 encodes the retinoblastoma protein (pRb), which inhibits CDKs and regulates the G1/S
checkpoint. Loss of heterozygosity of RB1 is common in many cancers, leading to unregulated cell cycle
progression. TP53 is involved in the G1/S checkpoint but acts upstream, not directly inhibiting CDKs.
PTEN regulates the PI3K/Akt pathway. APC is involved in Wnt signaling and beta-catenin degradation.
Page 2
,6. A patient with chronic kidney disease (stage 4) develops normocytic normochromic anemia.
Laboratory studies show low serum iron, low transferrin saturation, and low serum ferritin.
Which of the following is the most likely cause of the anemia?
A. Decreased erythropoietin production
B. Iron deficiency due to blood loss
C. Anemia of chronic disease
D. Folate deficiency
Answer: C
Rationale: In chronic kidney disease, anemia is often multifactorial, but the combination of low serum
iron, low transferrin saturation, and low ferritin is characteristic of iron deficiency, not anemia of
chronic disease (which would have high ferritin). However, in this scenario, the low ferritin indicates
iron deficiency, which can coexist with CKD. But the question states 'most likely cause' given the lab
values. Actually, low ferritin indicates depleted iron stores, so iron deficiency. However, in CKD, the
most common cause of anemia is decreased erythropoietin, which typically presents with normocytic
normochromic anemia and normal iron studies. The given labs suggest iron deficiency, which could be
due to blood loss. But option B says 'iron deficiency due to blood loss' which is plausible. However, the
question asks for the most likely cause. Given that the ferritin is low, it's iron deficiency. But in CKD, the
most common cause of anemia is EPO deficiency. The labs show low iron, low TSAT, low ferritin – that's
iron deficiency. So the cause is iron deficiency. But among options, B is iron deficiency due to blood
loss. However, the question might be testing anemia of chronic disease? No, low ferritin rules out ACD.
So I'll go with B. But let's re-read: 'low serum ferritin' – that indicates iron deficiency. So the anemia is
due to iron deficiency. In CKD, iron deficiency can be due to blood loss from uremic platelet
dysfunction. So B is correct. But the question says 'most likely cause' and the labs are classic for iron
deficiency. So answer B.
7. A patient with a history of recurrent sinopulmonary infections and autoimmune manifestations
is found to have a deficiency in the C3 component of complement. Which of the following is the
most likely consequence of this deficiency?
A. Impaired opsonization and phagocytosis of encapsulated bacteria
B. Deficient formation of the membrane attack complex (MAC)
C. Inability to form the alternative pathway C3 convertase
D. Increased susceptibility to viral infections due to impaired antibody-dependent cell-mediated cytotoxicity
Answer: A
Rationale: C3 is central to all complement pathways; its deficiency severely impairs opsonization (C3b),
leading to recurrent infections with encapsulated bacteria such as Streptococcus pneumoniae. MAC
formation is primarily dependent on C5-C9, but C3 deficiency also impairs MAC formation via the
classical and lectin pathways. However, the most critical clinical consequence is impaired opsonization.
Option B is also true but less direct clinically. Option C is true but not the most significant consequence.
Option D is not directly related to complement.
8. A 60-year-old individual is diagnosed with chronic obstructive pulmonary disease (COPD)
secondary to alpha-1 antitrypsin deficiency. Which of the following best describes the molecular
mechanism leading to lung tissue destruction?
Page 3
, A. Accumulation of misfolded alpha-1 antitrypsin in hepatocytes causing liver damage
B. Uninhibited neutrophil elastase activity leading to degradation of elastin in alveolar walls
C. Deficient production of surfactant by type II pneumocytes
D. Excessive collagen deposition by fibroblasts in response to chronic inflammation
Answer: B
Rationale: Alpha-1 antitrypsin is a serine protease inhibitor that neutralizes neutrophil elastase.
Deficiency leads to unchecked elastase activity, which degrades elastin and other extracellular matrix
components in the alveolar walls, causing emphysema. Option A describes the mechanism of liver
disease in alpha-1 antitrypsin deficiency but not lung destruction. Option C is associated with neonatal
respiratory distress syndrome. Option D describes pulmonary fibrosis.
9. A patient with type 2 diabetes mellitus develops a foot ulcer that becomes infected with
Staphylococcus aureus. The infection spreads to the bone, causing osteomyelitis. Which of the
following virulence factors produced by S. aureus is most directly responsible for its ability to
adhere to and colonize bone tissue?
A. Protein A
B. Coagulase
C. Fibronectin-binding proteins
D. Toxic shock syndrome toxin-1 (TSST-1)
Answer: C
Rationale: Fibronectin-binding proteins (FnBPs) on the surface of S. aureus mediate adherence to host
extracellular matrix components, including fibronectin and fibrinogen, which are abundant in bone. This
facilitates colonization and biofilm formation. Protein A binds immunoglobulins and evades
opsonization. Coagulase converts fibrinogen to fibrin, promoting clot formation and bacterial
protection. TSST-1 is a superantigen causing toxic shock syndrome.
10. A patient with a history of chronic alcoholism presents with confusion, ataxia, and nystagmus.
Thiamine deficiency is suspected. Which of the following metabolic pathways is most directly
impaired by thiamine deficiency, leading to the neurological symptoms?
A. Oxidative phosphorylation in the electron transport chain
B. Conversion of pyruvate to acetyl-CoA by pyruvate dehydrogenase
C. Synthesis of myelin basic protein in oligodendrocytes
D. Gamma-aminobutyric acid (GABA) synthesis in the cerebellum
Answer: B
Rationale: Thiamine (vitamin B1) is a cofactor for several enzymes, including pyruvate dehydrogenase,
alpha-ketoglutarate dehydrogenase, and transketolase. Impaired pyruvate dehydrogenase leads to
decreased acetyl-CoA production and ATP synthesis, particularly affecting high-energy-demand tissues
like the brain. This causes the neurological symptoms of Wernicke-Korsakoff syndrome. Option A is
indirectly affected but not directly. Options C and D are not directly dependent on thiamine.
Page 4
1-150 NR-507 ADVANCED PATHOPHYSIOLOGY
NR 507 WEEK 4 MIDTERM EXAM REVISED
ONLINE PROCTORED QUESTIONS AND
ANSWERS 100% GUARANTEED PASS..
1. A researcher is studying a signaling pathway in which a ligand binds to a receptor tyrosine
kinase (RTK), leading to activation of Ras and subsequent phosphorylation of ERK. Which of the
following mutations would most likely result in constitutive activation of this pathway independent
of ligand binding?
A. A gain-of-function mutation in the phosphatase that dephosphorylates ERK
B. A loss-of-function mutation in the GTPase-activating protein (GAP) for Ras
C. A loss-of-function mutation in the adaptor protein Grb2
D. A gain-of-function mutation in the guanine nucleotide exchange factor (GEF) for Ras
Answer: B
Rationale: A loss-of-function mutation in the GAP for Ras would impair the conversion of active
Ras-GTP to inactive Ras-GDP, leading to prolonged Ras signaling and constitutive pathway activation.
Option A would enhance ERK activity but is downstream. Option C would reduce signaling. Option D
could activate Ras but requires ligand binding to recruit GEF; a GEF gain-of-function mutation alone
may not cause constitutive activation without receptor activation.
2. A 45-year-old individual with a history of metabolic syndrome presents with acute chest pain.
Laboratory findings show elevated cardiac troponin I and a serum C-reactive protein (CRP) level
of 15 mg/L (normal <3 mg/L). Which of the following best describes the pathophysiological
sequence leading to the acute coronary event?
A. Endothelial dysfunction !’ decreased nitric oxide !’ platelet aggregation !’ thrombus formation
B. Macrophage foam cell apoptosis !’ lipid core expansion !’ plaque erosion !’ distal embolization
C. Plaque rupture !’ exposure of subendothelial collagen !’ platelet adhesion and activation !’ thrombus formation
D. Smooth muscle cell proliferation !’ intimal hyperplasia !’ critical stenosis !’ demand ischemia
Answer: C
Rationale: Acute coronary syndrome typically results from plaque rupture, exposing highly thrombogenic
subendothelial collagen, leading to platelet adhesion, activation, and thrombus formation. Elevated CRP
indicates systemic inflammation contributing to plaque instability. Option A describes early endothelial
dysfunction. Option B describes a mechanism for embolism from a lipid core but not the primary event.
Option D describes stable atherosclerosis and demand ischemia, not acute coronary syndrome.
Page 1
,3. Which of the following mechanisms best explains the development of hypocalcemia in a patient
with acute pancreatitis?
A. Increased renal excretion of calcium due to tubular damage
B. Sequestration of calcium in the form of calcium soaps in necrotic fat
C. Impaired intestinal absorption of calcium due to pancreatic enzyme deficiency
D. Increased calcitonin secretion from the thyroid in response to inflammation
Answer: B
Rationale: In acute pancreatitis, pancreatic enzymes (lipase) released into the peritoneum hydrolyze
triglycerides into free fatty acids, which then chelate calcium to form calcium soaps (saponification) in
necrotic adipose tissue, leading to hypocalcemia. Option A is not a primary mechanism. Option C
occurs in chronic pancreatitis. Option D is not a significant mechanism; calcitonin has a minor role in
calcium regulation.
4. A patient with a history of recurrent thromboembolism is found to have a prolonged activated
partial thromboplastin time (aPTT) that does not correct with mixing with normal plasma. Which
of the following is the most likely cause?
A. Factor VIII deficiency (hemophilia A)
B. Vitamin K deficiency
C. Lupus anticoagulant
D. Warfarin therapy
Answer: C
Rationale: Lupus anticoagulant is an antiphospholipid antibody that interferes with
phospholipid-dependent coagulation tests, causing a prolonged aPTT that does not correct with mixing
due to the presence of an inhibitor. Despite the in vitro prolongation, lupus anticoagulant is associated
with a prothrombotic state. Factor VIII deficiency would correct with mixing. Vitamin K deficiency and
warfarin affect the PT more than aPTT and correct with mixing.
5. A researcher is investigating a tumor suppressor gene that undergoes loss of heterozygosity
(LOH) in many cancers. The gene encodes a protein that inhibits cyclin-dependent kinases (CDKs)
and is involved in the G1/S checkpoint. Which of the following genes is most likely being studied?
A. TP53
B. RB1
C. PTEN
D. APC
Answer: B
Rationale: RB1 encodes the retinoblastoma protein (pRb), which inhibits CDKs and regulates the G1/S
checkpoint. Loss of heterozygosity of RB1 is common in many cancers, leading to unregulated cell cycle
progression. TP53 is involved in the G1/S checkpoint but acts upstream, not directly inhibiting CDKs.
PTEN regulates the PI3K/Akt pathway. APC is involved in Wnt signaling and beta-catenin degradation.
Page 2
,6. A patient with chronic kidney disease (stage 4) develops normocytic normochromic anemia.
Laboratory studies show low serum iron, low transferrin saturation, and low serum ferritin.
Which of the following is the most likely cause of the anemia?
A. Decreased erythropoietin production
B. Iron deficiency due to blood loss
C. Anemia of chronic disease
D. Folate deficiency
Answer: C
Rationale: In chronic kidney disease, anemia is often multifactorial, but the combination of low serum
iron, low transferrin saturation, and low ferritin is characteristic of iron deficiency, not anemia of
chronic disease (which would have high ferritin). However, in this scenario, the low ferritin indicates
iron deficiency, which can coexist with CKD. But the question states 'most likely cause' given the lab
values. Actually, low ferritin indicates depleted iron stores, so iron deficiency. However, in CKD, the
most common cause of anemia is decreased erythropoietin, which typically presents with normocytic
normochromic anemia and normal iron studies. The given labs suggest iron deficiency, which could be
due to blood loss. But option B says 'iron deficiency due to blood loss' which is plausible. However, the
question asks for the most likely cause. Given that the ferritin is low, it's iron deficiency. But in CKD, the
most common cause of anemia is EPO deficiency. The labs show low iron, low TSAT, low ferritin – that's
iron deficiency. So the cause is iron deficiency. But among options, B is iron deficiency due to blood
loss. However, the question might be testing anemia of chronic disease? No, low ferritin rules out ACD.
So I'll go with B. But let's re-read: 'low serum ferritin' – that indicates iron deficiency. So the anemia is
due to iron deficiency. In CKD, iron deficiency can be due to blood loss from uremic platelet
dysfunction. So B is correct. But the question says 'most likely cause' and the labs are classic for iron
deficiency. So answer B.
7. A patient with a history of recurrent sinopulmonary infections and autoimmune manifestations
is found to have a deficiency in the C3 component of complement. Which of the following is the
most likely consequence of this deficiency?
A. Impaired opsonization and phagocytosis of encapsulated bacteria
B. Deficient formation of the membrane attack complex (MAC)
C. Inability to form the alternative pathway C3 convertase
D. Increased susceptibility to viral infections due to impaired antibody-dependent cell-mediated cytotoxicity
Answer: A
Rationale: C3 is central to all complement pathways; its deficiency severely impairs opsonization (C3b),
leading to recurrent infections with encapsulated bacteria such as Streptococcus pneumoniae. MAC
formation is primarily dependent on C5-C9, but C3 deficiency also impairs MAC formation via the
classical and lectin pathways. However, the most critical clinical consequence is impaired opsonization.
Option B is also true but less direct clinically. Option C is true but not the most significant consequence.
Option D is not directly related to complement.
8. A 60-year-old individual is diagnosed with chronic obstructive pulmonary disease (COPD)
secondary to alpha-1 antitrypsin deficiency. Which of the following best describes the molecular
mechanism leading to lung tissue destruction?
Page 3
, A. Accumulation of misfolded alpha-1 antitrypsin in hepatocytes causing liver damage
B. Uninhibited neutrophil elastase activity leading to degradation of elastin in alveolar walls
C. Deficient production of surfactant by type II pneumocytes
D. Excessive collagen deposition by fibroblasts in response to chronic inflammation
Answer: B
Rationale: Alpha-1 antitrypsin is a serine protease inhibitor that neutralizes neutrophil elastase.
Deficiency leads to unchecked elastase activity, which degrades elastin and other extracellular matrix
components in the alveolar walls, causing emphysema. Option A describes the mechanism of liver
disease in alpha-1 antitrypsin deficiency but not lung destruction. Option C is associated with neonatal
respiratory distress syndrome. Option D describes pulmonary fibrosis.
9. A patient with type 2 diabetes mellitus develops a foot ulcer that becomes infected with
Staphylococcus aureus. The infection spreads to the bone, causing osteomyelitis. Which of the
following virulence factors produced by S. aureus is most directly responsible for its ability to
adhere to and colonize bone tissue?
A. Protein A
B. Coagulase
C. Fibronectin-binding proteins
D. Toxic shock syndrome toxin-1 (TSST-1)
Answer: C
Rationale: Fibronectin-binding proteins (FnBPs) on the surface of S. aureus mediate adherence to host
extracellular matrix components, including fibronectin and fibrinogen, which are abundant in bone. This
facilitates colonization and biofilm formation. Protein A binds immunoglobulins and evades
opsonization. Coagulase converts fibrinogen to fibrin, promoting clot formation and bacterial
protection. TSST-1 is a superantigen causing toxic shock syndrome.
10. A patient with a history of chronic alcoholism presents with confusion, ataxia, and nystagmus.
Thiamine deficiency is suspected. Which of the following metabolic pathways is most directly
impaired by thiamine deficiency, leading to the neurological symptoms?
A. Oxidative phosphorylation in the electron transport chain
B. Conversion of pyruvate to acetyl-CoA by pyruvate dehydrogenase
C. Synthesis of myelin basic protein in oligodendrocytes
D. Gamma-aminobutyric acid (GABA) synthesis in the cerebellum
Answer: B
Rationale: Thiamine (vitamin B1) is a cofactor for several enzymes, including pyruvate dehydrogenase,
alpha-ketoglutarate dehydrogenase, and transketolase. Impaired pyruvate dehydrogenase leads to
decreased acetyl-CoA production and ATP synthesis, particularly affecting high-energy-demand tissues
like the brain. This causes the neurological symptoms of Wernicke-Korsakoff syndrome. Option A is
indirectly affected but not directly. Options C and D are not directly dependent on thiamine.
Page 4
