WGU D236 PATHOPHYSIOLOGY OA TEST
BANK 2026/2027: VERIFIED QUESTIONS &
ANSWERS
SECTION 1: Cellular Biology & Foundations
Q1: A trauma patient develops profuse vomiting and diarrhea. ABG: pH 7.29, PaCO₂ 40
mmHg, HCO₃⁻ 17 mEq/L. Which mechanism best explains the acid–base disturbance?
A. Alveolar hypoventilation retaining CO₂
B. Renal excretion of fixed acids failing
C. Intestinal bicarbonate loss plus acid accumulation
D. Excessive diuretic-induced chloride depletion
Correct Answer: C
Rationale: Disease/Process: Metabolic acidosis secondary to gastrointestinal fluid loss.
Pathophysiological Sequence: Severe vomiting and diarrhea (etiology) cause direct loss
of bicarbonate-rich intestinal and pancreatic secretions while also creating volume
contraction that impairs renal acid excretion (pathogenesis). The result is a primary
decrease in serum HCO₃⁻ and compensatory neutral PaCO₂ (not yet compensated),
yielding pH 7.29. Distractor Analysis: A describes respiratory acidosis (↑PaCO₂), which
is absent. B suggests renal failure, but creatinine is not mentioned and the primary drive
is GI loss. D would produce metabolic alkalosis, not acidosis.
Q2: After 48 h of persistent vomiting, a patient’s ABG shows pH 7.48, PaCO₂ 48 mmHg,
HCO₃⁻ 34 mEq/L. Which pathophysiological event is the primary driver of the pH
change?
,A. Gastric acid loss leading to chloride-responsive alkalosis
B. Hyperventilation washing out CO₂
C. Lactic acid overproduction
D. Increased aldosterone secreting excess H⁺
Correct Answer: A
Rationale: Disease/Process: Chloride-responsive metabolic alkalosis. Sequence:
Vomiting (etiology) loses hydrochloric acid from the stomach, raising plasma HCO₃⁻ and
pH (pathogenesis). The kidney attempts to retain CO₂ (↑PaCO₂) as respiratory
compensation. Distractors: B is respiratory alkalosis (↑pH, ↓PaCO₂) – here PaCO₂ is
elevated. C produces metabolic acidosis. D can maintain but not initiate the alkalosis;
the primary event is acid loss.
Q3: A diabetic patient’s blood reveals: Na⁺ 132 mEq/L, glucose 600 mg/dL, serum
osmolality 318 mOsm/kg. Which mechanism best accounts for the hyponatremia?
A. ADH-driven water retention
B. Osmotic shift drawing intracellular water into plasma
C. Renal sodium wasting from osmotic diuresis
D. Dilutional effect of infused isotonic saline
Correct Answer: B
Rationale: Process: Hyperglycemia-induced pseudohyponatremia. Sequence: Extreme
hyperglycecemia (etiology) raises extracellular osmolality, causing osmotic shift of water
from intracellular to extracellular compartment (pathogenesis). The added water dilutes
sodium concentration, yielding measured hyponatremia without net sodium loss.
, Distractors: A contributes in DKA/HHS but is secondary to osmotic diuresis; C causes
true Na loss (would see lower osmolality); D would raise, not lower, Na.
Q4: A genetic disorder shows anticipation with expanding trinucleotide (CGG) repeats in
successive generations. Which concept best explains earlier onset and increased
severity?
A. Incomplete penetrance
B. Expansion during meiosis in germ cells
C. Genomic imprinting
D. Loss of heterozygosity
Correct Answer: B
Rationale: Disease example: Fragile X syndrome. Mechanism: Trinucleotide repeat
expansion (etiology) occurs during spermatogenesis/oogenesis due to slipped-strand
mispairing (pathogenesis), enlarging the repeat in gametes. The larger repeat in
offspring leads to earlier transcriptional silencing and more severe phenotype.
Distractors: A describes variable expression, not progression; C involves
parent-of-origin effects; D is tumor suppressor mechanism.
Q5: A cell exposed to chronic irritation undergoes conversion from columnar to stratified
squamous epithelium. This adaptive change is termed:
A. Dysplasia
B. Metaplasia
C. Hyperplasia
D. Anaplasia
BANK 2026/2027: VERIFIED QUESTIONS &
ANSWERS
SECTION 1: Cellular Biology & Foundations
Q1: A trauma patient develops profuse vomiting and diarrhea. ABG: pH 7.29, PaCO₂ 40
mmHg, HCO₃⁻ 17 mEq/L. Which mechanism best explains the acid–base disturbance?
A. Alveolar hypoventilation retaining CO₂
B. Renal excretion of fixed acids failing
C. Intestinal bicarbonate loss plus acid accumulation
D. Excessive diuretic-induced chloride depletion
Correct Answer: C
Rationale: Disease/Process: Metabolic acidosis secondary to gastrointestinal fluid loss.
Pathophysiological Sequence: Severe vomiting and diarrhea (etiology) cause direct loss
of bicarbonate-rich intestinal and pancreatic secretions while also creating volume
contraction that impairs renal acid excretion (pathogenesis). The result is a primary
decrease in serum HCO₃⁻ and compensatory neutral PaCO₂ (not yet compensated),
yielding pH 7.29. Distractor Analysis: A describes respiratory acidosis (↑PaCO₂), which
is absent. B suggests renal failure, but creatinine is not mentioned and the primary drive
is GI loss. D would produce metabolic alkalosis, not acidosis.
Q2: After 48 h of persistent vomiting, a patient’s ABG shows pH 7.48, PaCO₂ 48 mmHg,
HCO₃⁻ 34 mEq/L. Which pathophysiological event is the primary driver of the pH
change?
,A. Gastric acid loss leading to chloride-responsive alkalosis
B. Hyperventilation washing out CO₂
C. Lactic acid overproduction
D. Increased aldosterone secreting excess H⁺
Correct Answer: A
Rationale: Disease/Process: Chloride-responsive metabolic alkalosis. Sequence:
Vomiting (etiology) loses hydrochloric acid from the stomach, raising plasma HCO₃⁻ and
pH (pathogenesis). The kidney attempts to retain CO₂ (↑PaCO₂) as respiratory
compensation. Distractors: B is respiratory alkalosis (↑pH, ↓PaCO₂) – here PaCO₂ is
elevated. C produces metabolic acidosis. D can maintain but not initiate the alkalosis;
the primary event is acid loss.
Q3: A diabetic patient’s blood reveals: Na⁺ 132 mEq/L, glucose 600 mg/dL, serum
osmolality 318 mOsm/kg. Which mechanism best accounts for the hyponatremia?
A. ADH-driven water retention
B. Osmotic shift drawing intracellular water into plasma
C. Renal sodium wasting from osmotic diuresis
D. Dilutional effect of infused isotonic saline
Correct Answer: B
Rationale: Process: Hyperglycemia-induced pseudohyponatremia. Sequence: Extreme
hyperglycecemia (etiology) raises extracellular osmolality, causing osmotic shift of water
from intracellular to extracellular compartment (pathogenesis). The added water dilutes
sodium concentration, yielding measured hyponatremia without net sodium loss.
, Distractors: A contributes in DKA/HHS but is secondary to osmotic diuresis; C causes
true Na loss (would see lower osmolality); D would raise, not lower, Na.
Q4: A genetic disorder shows anticipation with expanding trinucleotide (CGG) repeats in
successive generations. Which concept best explains earlier onset and increased
severity?
A. Incomplete penetrance
B. Expansion during meiosis in germ cells
C. Genomic imprinting
D. Loss of heterozygosity
Correct Answer: B
Rationale: Disease example: Fragile X syndrome. Mechanism: Trinucleotide repeat
expansion (etiology) occurs during spermatogenesis/oogenesis due to slipped-strand
mispairing (pathogenesis), enlarging the repeat in gametes. The larger repeat in
offspring leads to earlier transcriptional silencing and more severe phenotype.
Distractors: A describes variable expression, not progression; C involves
parent-of-origin effects; D is tumor suppressor mechanism.
Q5: A cell exposed to chronic irritation undergoes conversion from columnar to stratified
squamous epithelium. This adaptive change is termed:
A. Dysplasia
B. Metaplasia
C. Hyperplasia
D. Anaplasia
