WGU D313 Anatomy and Physiology II
Objective Assessment Exam
2026/2027 Newly Released
70 Verified Questions with answers and expert rationales
Q1: A patient presents with excessive thirst, frequent urination of large volumes of dilute urine,
and serum sodium of 152 mEq/L. Laboratory tests reveal low ADH levels. Which diagnosis is
most consistent with these findings?
A. SIADH
B. Diabetes insipidus [CORRECT]
C. Psychogenic polydipsia
D. Diabetes mellitus Type 2
Correct Answer: B
Rationale: Correct because diabetes insipidus results from either insufficient ADH production
(central DI) or renal unresponsiveness to ADH (nephrogenic DI), causing the kidneys to excrete
large volumes of dilute urine, triggering compensatory polydipsia and hypernatremia. SIADH
causes the opposite pattern—water retention and hyponatremia—while diabetes mellitus
involves glucose in the urine, not dilute urine with low ADH. Psychogenic polydipsia produces
dilute urine but with normal or suppressed ADH from voluntary overconsumption of water.
Q2: Trace the path of a drop of blood from the right atrium through the pulmonary circuit and
back to the left atrium. Which sequence is correct?
A. Right atrium → right ventricle → pulmonary trunk → pulmonary arteries → lungs →
pulmonary veins → left atrium [CORRECT]
B. Right atrium → left ventricle → aorta → pulmonary arteries → lungs → pulmonary veins →
left atrium
C. Right atrium → right ventricle → aorta → lungs → pulmonary veins → left atrium
D. Right atrium → left atrium → right ventricle → pulmonary trunk → lungs → pulmonary veins
,Correct Answer: A
Rationale: Correct because deoxygenated blood enters the right atrium via the superior and
inferior vena cavae, passes through the tricuspid valve into the right ventricle, is pumped
through the pulmonary valve into the pulmonary trunk, travels via the pulmonary arteries to
the lungs for gas exchange, and returns oxygenated via the pulmonary veins to the left atrium.
The aorta carries blood from the left ventricle to the systemic circuit, not the pulmonary circuit,
and blood cannot flow directly from the right atrium to the left ventricle.
Q3: Which type of hormone receptor is used by lipid-soluble hormones such as cortisol and
thyroid hormones?
A. G-protein coupled receptors on the cell membrane
B. Receptor tyrosine kinases on the cell surface
C. Intracellular receptors (cytoplasmic or nuclear) that directly affect gene transcription
[CORRECT]
D. Ligand-gated ion channels
Correct Answer: C
Rationale: Correct because lipid-soluble hormones (steroid hormones like cortisol, aldosterone,
testosterone, and thyroid hormones T3/T4) diffuse across the plasma membrane and bind to
intracellular receptors in the cytoplasm or nucleus, forming hormone-receptor complexes that
act as transcription factors to directly regulate gene expression—a genomic mechanism that
takes hours to days. Water-soluble hormones use membrane receptors: G-protein coupled
receptors activate second messengers like cAMP, receptor tyrosine kinases activate
phosphorylation cascades, and ligand-gated ion channels allow direct ion flow.
Q4: A patient with emphysema undergoes spirometry. Which result is most expected?
A. FEV1/FVC ratio normal, decreased vital capacity
B. Normal FEV1/FVC ratio, normal total lung capacity
C. Increased FEV1/FVC ratio, decreased residual volume
D. Decreased FEV1/FVC ratio, increased total lung capacity [CORRECT]
Correct Answer: D
,Rationale: Correct because emphysema is an obstructive lung disease characterized by
destruction of alveolar walls and loss of elastic recoil, which causes airway collapse during
expiration and air trapping—resulting in a decreased FEV1/FVC ratio (the hallmark of
obstruction) and an increased total lung capacity due to hyperinflation. Restrictive diseases like
pulmonary fibrosis show a normal or increased FEV1/FVC ratio with decreased vital capacity,
not the obstructive pattern seen here.
Q5: In the nephron, the majority of tubular reabsorption (approximately 65% of filtered solutes
and water) occurs in which segment?
A. Loop of Henle
B. Distal convoluted tubule
C. Proximal convoluted tubule [CORRECT]
D. Collecting duct
Correct Answer: C
Rationale: Correct because the proximal convoluted tubule (PCT) is the primary site of tubular
reabsorption, recovering approximately 65% of filtered sodium, water, glucose, amino acids,
and bicarbonate via both active transport and osmotic follow-through. The Loop of Henle
establishes the medullary concentration gradient, the DCT performs fine-tuning under
hormonal control (aldosterone, ADH), and the collecting duct performs final water reabsorption
under ADH regulation—but none reabsorb as much as the PCT.
Q6: Which immunoglobulin class is the first to be produced during a primary immune response
and is most effective at agglutination?
A. IgG
B. IgA
C. IgM [CORRECT]
D. IgE
Correct Answer: C
Rationale: Correct because IgM is the first antibody produced during a primary immune
response, appearing within days of antigen exposure; it is a pentamer with ten antigen-binding
, sites, making it extremely effective at agglutination (clumping pathogens) and complement
activation. IgG is the most abundant antibody in secondary responses, IgA is found in mucosal
secretions, and IgE mediates allergic reactions and parasitic defense—none are the first
responders in a primary response.
Q7: During the luteal phase of the menstrual cycle, which hormone is at its peak and maintains
the endometrial lining?
A. FSH
B. Estrogen
C. Progesterone [CORRECT]
D. LH
Correct Answer: C
Rationale: Correct because after ovulation, the corpus luteum secretes large amounts of
progesterone, which peaks during the luteal phase (days 15–28) and maintains the thickened,
secretory endometrium in preparation for potential implantation. If pregnancy does not occur,
the corpus luteum degenerates, progesterone drops, and menstruation begins. FSH and LH peak
earlier (follicular phase and ovulation respectively), and estrogen peaks just before ovulation,
not during the luteal phase.
Q8: A patient's arterial blood gas shows pH 7.30, PaCO2 50 mmHg, and HCO3– 24 mEq/L. Which
acid-base disorder is present?
A. Metabolic acidosis
B. Metabolic alkalosis
C. Respiratory acidosis [CORRECT]
D. Respiratory alkalosis
Correct Answer: C
Rationale: Correct because the pH of 7.30 is below normal (7.35–7.45) indicating acidosis, the
PaCO2 of 50 mmHg is elevated above normal (35–45 mmHg) indicating a respiratory cause, and
the HCO3– of 24 mEq/L is normal, indicating no metabolic compensation has occurred yet—this
is uncompensated respiratory acidosis. Metabolic acidosis would show low HCO3–, metabolic
Objective Assessment Exam
2026/2027 Newly Released
70 Verified Questions with answers and expert rationales
Q1: A patient presents with excessive thirst, frequent urination of large volumes of dilute urine,
and serum sodium of 152 mEq/L. Laboratory tests reveal low ADH levels. Which diagnosis is
most consistent with these findings?
A. SIADH
B. Diabetes insipidus [CORRECT]
C. Psychogenic polydipsia
D. Diabetes mellitus Type 2
Correct Answer: B
Rationale: Correct because diabetes insipidus results from either insufficient ADH production
(central DI) or renal unresponsiveness to ADH (nephrogenic DI), causing the kidneys to excrete
large volumes of dilute urine, triggering compensatory polydipsia and hypernatremia. SIADH
causes the opposite pattern—water retention and hyponatremia—while diabetes mellitus
involves glucose in the urine, not dilute urine with low ADH. Psychogenic polydipsia produces
dilute urine but with normal or suppressed ADH from voluntary overconsumption of water.
Q2: Trace the path of a drop of blood from the right atrium through the pulmonary circuit and
back to the left atrium. Which sequence is correct?
A. Right atrium → right ventricle → pulmonary trunk → pulmonary arteries → lungs →
pulmonary veins → left atrium [CORRECT]
B. Right atrium → left ventricle → aorta → pulmonary arteries → lungs → pulmonary veins →
left atrium
C. Right atrium → right ventricle → aorta → lungs → pulmonary veins → left atrium
D. Right atrium → left atrium → right ventricle → pulmonary trunk → lungs → pulmonary veins
,Correct Answer: A
Rationale: Correct because deoxygenated blood enters the right atrium via the superior and
inferior vena cavae, passes through the tricuspid valve into the right ventricle, is pumped
through the pulmonary valve into the pulmonary trunk, travels via the pulmonary arteries to
the lungs for gas exchange, and returns oxygenated via the pulmonary veins to the left atrium.
The aorta carries blood from the left ventricle to the systemic circuit, not the pulmonary circuit,
and blood cannot flow directly from the right atrium to the left ventricle.
Q3: Which type of hormone receptor is used by lipid-soluble hormones such as cortisol and
thyroid hormones?
A. G-protein coupled receptors on the cell membrane
B. Receptor tyrosine kinases on the cell surface
C. Intracellular receptors (cytoplasmic or nuclear) that directly affect gene transcription
[CORRECT]
D. Ligand-gated ion channels
Correct Answer: C
Rationale: Correct because lipid-soluble hormones (steroid hormones like cortisol, aldosterone,
testosterone, and thyroid hormones T3/T4) diffuse across the plasma membrane and bind to
intracellular receptors in the cytoplasm or nucleus, forming hormone-receptor complexes that
act as transcription factors to directly regulate gene expression—a genomic mechanism that
takes hours to days. Water-soluble hormones use membrane receptors: G-protein coupled
receptors activate second messengers like cAMP, receptor tyrosine kinases activate
phosphorylation cascades, and ligand-gated ion channels allow direct ion flow.
Q4: A patient with emphysema undergoes spirometry. Which result is most expected?
A. FEV1/FVC ratio normal, decreased vital capacity
B. Normal FEV1/FVC ratio, normal total lung capacity
C. Increased FEV1/FVC ratio, decreased residual volume
D. Decreased FEV1/FVC ratio, increased total lung capacity [CORRECT]
Correct Answer: D
,Rationale: Correct because emphysema is an obstructive lung disease characterized by
destruction of alveolar walls and loss of elastic recoil, which causes airway collapse during
expiration and air trapping—resulting in a decreased FEV1/FVC ratio (the hallmark of
obstruction) and an increased total lung capacity due to hyperinflation. Restrictive diseases like
pulmonary fibrosis show a normal or increased FEV1/FVC ratio with decreased vital capacity,
not the obstructive pattern seen here.
Q5: In the nephron, the majority of tubular reabsorption (approximately 65% of filtered solutes
and water) occurs in which segment?
A. Loop of Henle
B. Distal convoluted tubule
C. Proximal convoluted tubule [CORRECT]
D. Collecting duct
Correct Answer: C
Rationale: Correct because the proximal convoluted tubule (PCT) is the primary site of tubular
reabsorption, recovering approximately 65% of filtered sodium, water, glucose, amino acids,
and bicarbonate via both active transport and osmotic follow-through. The Loop of Henle
establishes the medullary concentration gradient, the DCT performs fine-tuning under
hormonal control (aldosterone, ADH), and the collecting duct performs final water reabsorption
under ADH regulation—but none reabsorb as much as the PCT.
Q6: Which immunoglobulin class is the first to be produced during a primary immune response
and is most effective at agglutination?
A. IgG
B. IgA
C. IgM [CORRECT]
D. IgE
Correct Answer: C
Rationale: Correct because IgM is the first antibody produced during a primary immune
response, appearing within days of antigen exposure; it is a pentamer with ten antigen-binding
, sites, making it extremely effective at agglutination (clumping pathogens) and complement
activation. IgG is the most abundant antibody in secondary responses, IgA is found in mucosal
secretions, and IgE mediates allergic reactions and parasitic defense—none are the first
responders in a primary response.
Q7: During the luteal phase of the menstrual cycle, which hormone is at its peak and maintains
the endometrial lining?
A. FSH
B. Estrogen
C. Progesterone [CORRECT]
D. LH
Correct Answer: C
Rationale: Correct because after ovulation, the corpus luteum secretes large amounts of
progesterone, which peaks during the luteal phase (days 15–28) and maintains the thickened,
secretory endometrium in preparation for potential implantation. If pregnancy does not occur,
the corpus luteum degenerates, progesterone drops, and menstruation begins. FSH and LH peak
earlier (follicular phase and ovulation respectively), and estrogen peaks just before ovulation,
not during the luteal phase.
Q8: A patient's arterial blood gas shows pH 7.30, PaCO2 50 mmHg, and HCO3– 24 mEq/L. Which
acid-base disorder is present?
A. Metabolic acidosis
B. Metabolic alkalosis
C. Respiratory acidosis [CORRECT]
D. Respiratory alkalosis
Correct Answer: C
Rationale: Correct because the pH of 7.30 is below normal (7.35–7.45) indicating acidosis, the
PaCO2 of 50 mmHg is elevated above normal (35–45 mmHg) indicating a respiratory cause, and
the HCO3– of 24 mEq/L is normal, indicating no metabolic compensation has occurred yet—this
is uncompensated respiratory acidosis. Metabolic acidosis would show low HCO3–, metabolic
