WGU D236 Pathophysiology OA Actual Exam
2026/2027 | Questions with Verified Answers |
100% Correct | Pass Guaranteed
SECTION 1: Cellular Biology & Foundations
Q1: A patient with prolonged vomiting presents with weakness and muscle cramps.
ABG: pH 7.50, PaCO₂ 46 mm Hg, HCO₃⁻ 34 mEq/L. Which pathophysiologic mechanism
best explains the alkalosis?
A. Hyperventilation-induced hypocapnia
B. Renal compensation for acid overload
C. Gastric acid loss → ↑ HCO₃⁻ reabsorption & generation
D. Lactic acid buildup
Correct Answer: C
Rationale: Disease/Process: Metabolic alkalosis from vomiting. Pathophysiological
Sequence: Vomiting (etiology) causes loss of gastric HCl, raising plasma bicarbonate
(pathogenesis). Kidneys compensate by increasing HCO₃⁻ reabsorption and generating
new bicarbonate via increased distal H⁺ secretion, maintaining the elevated HCO₃⁻ (34
mEq/L) and high pH. The slight rise in PaCO₂ (46 mm Hg) reflects respiratory
compensation. Distractor Analysis: A describes respiratory alkalosis (low PaCO₂). B
implies acid overload, which would lower HCO₃⁻. D produces metabolic acidosis, not
alkalosis.
,Q2: A marathon runner collapses and drinks large volumes of water without electrolyte
replacement. Na⁺ 128 mEq/L, serum osmolality 260 mOsm/kg. Which cellular response
will occur in neurons?
A. Water moves into cells → cerebral edema
B. Water moves out of cells → shrinkage
C. Sodium moves into cells → depolarization block
D. Potassium moves out → hyperpolarization
Correct Answer: A
Rationale: Disease/Process: Exercise-associated hyponatremia. Pathophysiological
Sequence: Excess free water (etiology) lowers plasma osmolality below intracellular
osmolality, creating an osmotic gradient (pathogenesis). Water shifts into brain cells,
causing cerebral edema (clinical manifestation: confusion, seizures). Distractor
Analysis: B occurs in hypernatremia. C and D describe ion-channel events unrelated to
osmotic shifts.
Q3: A genetic defect causes inability to convert phenylalanine to tyrosine. Accumulated
metabolites damage developing neurons. Which pathophysiologic term best describes
this mechanism?
A. Apoptosis from oncogene activation
B. Toxic metabolite-induced injury → energy failure
C. Ischemic necrosis from vessel occlusion
D. Autoimmune demyelination
,Correct Answer: B
Rationale: Disease/Process: Phenylketonuria (PKU). Pathophysiological Sequence:
Phenylalanine hydroxylase deficiency (etiology) → phenylalanine and its keto-acids
accumulate (pathogenesis) → inhibit glucose metabolism and myelination in brain →
neuronal dysfunction (clinical: intellectual disability). Distractor Analysis: A is
cancer-related. C is vascular. D is immune-mediated (e.g., MS).
Q4: A tumor suppressor gene is deleted in a colon epithelial cell. Subsequent mutations
activate KRAS and inactivate TP53. Which sequence best explains malignant
transformation?
A. Loss of gatekeeper → unchecked proliferation → genomic instability → invasion
B. Oncogene inactivation first → apoptosis → regression
C. Telomere lengthening → senescence
D. Apoptosis amplification → adenoma
Correct Answer: A
Rationale: Disease/Process: Colorectal carcinogenesis (adenoma-carcinoma
sequence). Pathophysiological Sequence: Loss of APC (gatekeeper) removes growth
control (pathogenesis), allowing proliferation. KRAS activation enhances survival, and
TP53 loss removes DNA-damage checkpoint, enabling invasion (clinical: carcinoma).
Distractor Analysis: B reverses the oncogene role. C describes aging, not cancer. D
implies growth suppression, not progression.
Q5: A patient with CKD stage 4 develops acidosis. Which primary renal mechanism
underlies the inability to excrete daily acid load?
, A. ↓ NH₄⁺ excretion → impaired net acid secretion
B. ↑ Bicarbonate filtration
C. Respiratory compensation failure
D. Lactic acid overproduction
Correct Answer: A
Rationale: Disease/Process: Renal tubular acidosis of CKD. Pathophysiological
Sequence: Diseased kidneys (etiology) have reduced functional mass → ↓ distal tubular
NH₃ synthesis (pathogenesis) → ↓ NH₄⁺ in urine → net acid excretion falls below daily
production → metabolic acidosis (low pH, low HCO₃⁻). Distractor Analysis: B would
improve acidosis. C is compensatory, not causative. D is secondary, not primary renal.
Q6: A 60-year-old smoker presents with clubbing and a new solid 2 cm lung nodule.
Biopsy shows polygonal cells with abundant mitoses and necrosis. Which cellular
process is most characteristic of this malignancy?
A. Apoptosis resistance → clonal expansion
B. Physiologic hyperplasia
C. Metaplasia of bronchial glands
D. Coagulative necrosis of tumor
Correct Answer: A
Rationale: Disease/Process: Small-cell carcinoma. Pathophysiological Sequence:
Mutations (e.g., TP53, RB1) disable apoptosis (pathogenesis), allowing rapid
proliferation and accumulation of mitoses/necrosis (clinical: high-grade malignancy).
2026/2027 | Questions with Verified Answers |
100% Correct | Pass Guaranteed
SECTION 1: Cellular Biology & Foundations
Q1: A patient with prolonged vomiting presents with weakness and muscle cramps.
ABG: pH 7.50, PaCO₂ 46 mm Hg, HCO₃⁻ 34 mEq/L. Which pathophysiologic mechanism
best explains the alkalosis?
A. Hyperventilation-induced hypocapnia
B. Renal compensation for acid overload
C. Gastric acid loss → ↑ HCO₃⁻ reabsorption & generation
D. Lactic acid buildup
Correct Answer: C
Rationale: Disease/Process: Metabolic alkalosis from vomiting. Pathophysiological
Sequence: Vomiting (etiology) causes loss of gastric HCl, raising plasma bicarbonate
(pathogenesis). Kidneys compensate by increasing HCO₃⁻ reabsorption and generating
new bicarbonate via increased distal H⁺ secretion, maintaining the elevated HCO₃⁻ (34
mEq/L) and high pH. The slight rise in PaCO₂ (46 mm Hg) reflects respiratory
compensation. Distractor Analysis: A describes respiratory alkalosis (low PaCO₂). B
implies acid overload, which would lower HCO₃⁻. D produces metabolic acidosis, not
alkalosis.
,Q2: A marathon runner collapses and drinks large volumes of water without electrolyte
replacement. Na⁺ 128 mEq/L, serum osmolality 260 mOsm/kg. Which cellular response
will occur in neurons?
A. Water moves into cells → cerebral edema
B. Water moves out of cells → shrinkage
C. Sodium moves into cells → depolarization block
D. Potassium moves out → hyperpolarization
Correct Answer: A
Rationale: Disease/Process: Exercise-associated hyponatremia. Pathophysiological
Sequence: Excess free water (etiology) lowers plasma osmolality below intracellular
osmolality, creating an osmotic gradient (pathogenesis). Water shifts into brain cells,
causing cerebral edema (clinical manifestation: confusion, seizures). Distractor
Analysis: B occurs in hypernatremia. C and D describe ion-channel events unrelated to
osmotic shifts.
Q3: A genetic defect causes inability to convert phenylalanine to tyrosine. Accumulated
metabolites damage developing neurons. Which pathophysiologic term best describes
this mechanism?
A. Apoptosis from oncogene activation
B. Toxic metabolite-induced injury → energy failure
C. Ischemic necrosis from vessel occlusion
D. Autoimmune demyelination
,Correct Answer: B
Rationale: Disease/Process: Phenylketonuria (PKU). Pathophysiological Sequence:
Phenylalanine hydroxylase deficiency (etiology) → phenylalanine and its keto-acids
accumulate (pathogenesis) → inhibit glucose metabolism and myelination in brain →
neuronal dysfunction (clinical: intellectual disability). Distractor Analysis: A is
cancer-related. C is vascular. D is immune-mediated (e.g., MS).
Q4: A tumor suppressor gene is deleted in a colon epithelial cell. Subsequent mutations
activate KRAS and inactivate TP53. Which sequence best explains malignant
transformation?
A. Loss of gatekeeper → unchecked proliferation → genomic instability → invasion
B. Oncogene inactivation first → apoptosis → regression
C. Telomere lengthening → senescence
D. Apoptosis amplification → adenoma
Correct Answer: A
Rationale: Disease/Process: Colorectal carcinogenesis (adenoma-carcinoma
sequence). Pathophysiological Sequence: Loss of APC (gatekeeper) removes growth
control (pathogenesis), allowing proliferation. KRAS activation enhances survival, and
TP53 loss removes DNA-damage checkpoint, enabling invasion (clinical: carcinoma).
Distractor Analysis: B reverses the oncogene role. C describes aging, not cancer. D
implies growth suppression, not progression.
Q5: A patient with CKD stage 4 develops acidosis. Which primary renal mechanism
underlies the inability to excrete daily acid load?
, A. ↓ NH₄⁺ excretion → impaired net acid secretion
B. ↑ Bicarbonate filtration
C. Respiratory compensation failure
D. Lactic acid overproduction
Correct Answer: A
Rationale: Disease/Process: Renal tubular acidosis of CKD. Pathophysiological
Sequence: Diseased kidneys (etiology) have reduced functional mass → ↓ distal tubular
NH₃ synthesis (pathogenesis) → ↓ NH₄⁺ in urine → net acid excretion falls below daily
production → metabolic acidosis (low pH, low HCO₃⁻). Distractor Analysis: B would
improve acidosis. C is compensatory, not causative. D is secondary, not primary renal.
Q6: A 60-year-old smoker presents with clubbing and a new solid 2 cm lung nodule.
Biopsy shows polygonal cells with abundant mitoses and necrosis. Which cellular
process is most characteristic of this malignancy?
A. Apoptosis resistance → clonal expansion
B. Physiologic hyperplasia
C. Metaplasia of bronchial glands
D. Coagulative necrosis of tumor
Correct Answer: A
Rationale: Disease/Process: Small-cell carcinoma. Pathophysiological Sequence:
Mutations (e.g., TP53, RB1) disable apoptosis (pathogenesis), allowing rapid
proliferation and accumulation of mitoses/necrosis (clinical: high-grade malignancy).
