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WGU D115 Advanced Pathophysiology
Sample Questions 2025 – 400 Practice
Questions for Units 2–7 with Verified
Answers & Detailed Rationales | A+ Graded
Question 1
Which cells primarily mediate the body's defense against parasitic infections?
A) Neutrophils
B) Eosinophils
C) Basophils
D) Macrophages
Rationale: Eosinophils are specialized for combating parasitic infections, particularly helminths,
by releasing cytotoxic granules. Neutrophils target bacteria, basophils are involved in allergic
responses, and macrophages phagocytose bacteria and debris.
Question 2
What is the primary mechanism by which erythrocytes are destroyed in ABO blood
incompatibility?
A) Direct hemolysis by cytotoxic T cells
B) Activation of the complement pathway
C) Phagocytosis by neutrophils
D) Oxidative stress from reactive oxygen species
Rationale: The complement pathway is activated by antigen-antibody complexes in ABO
incompatibility, leading to erythrocyte lysis. T cells are not primarily involved, neutrophils target
bacteria, and oxidative stress is not the main mechanism.
Question 3
Which characteristic is the most critical determinant of an antigen’s immunogenicity?
A) Molecular weight
B) Ability to be recognized as foreign
C) Chemical composition
D) Solubility in plasma
Rationale: Immunogenicity depends on the immune system recognizing an antigen as foreign,
triggering a response. Molecular weight, composition, and solubility contribute but are secondary
to foreignness.
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Question 4
What is the earliest time frame for detecting HIV infection via RNA testing after sexual
transmission?
A) 1–3 days
B) 4–10 days
C) 11–15 days
D) 16–20 days
Rationale: HIV RNA can be detected 4–10 days post-transmission using nucleic acid
amplification tests, earlier than antibody tests (23–90 days). Testing too soon may yield false
negatives, requiring repeat testing.
Question 5
Which genetic disorder is caused by a deletion on the short arm of chromosome 5, presenting
with a high-pitched, cat-like cry in infancy?
A) Turner syndrome
B) Cri du chat syndrome
C) Down syndrome
D) Klinefelter syndrome
Rationale: Cri du chat syndrome results from a deletion on chromosome 5p, leading to
characteristic features like a cat-like cry, microcephaly, and developmental delays. Other options
involve different chromosomal abnormalities.
Question 6
What is the primary pathophysiological cause of hypertension?
A) Decreased cardiac output
B) Increased cardiac output or peripheral resistance
C) Reduced blood viscosity
D) Impaired baroreceptor function
Rationale: Hypertension is driven by increased cardiac output (e.g., from elevated heart rate or
stroke volume) or increased peripheral resistance (e.g., from vasoconstriction). Reduced
viscosity or baroreceptor issues are not primary causes.
Question 7
Which condition is characterized by a creamy appearance of retinal vessels and serum
triglyceride levels exceeding 2,500 mg/dL?
A) Diabetic retinopathy
B) Hypertriglyceridemia
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C) Hypertensive retinopathy
D) Central retinal vein occlusion
Rationale: Hypertriglyceridemia causes a creamy appearance of retinal vessels (lipemia
retinalis) due to high triglyceride levels. Other conditions affect retinal vessels differently and are
not associated with such triglyceride levels.
Question 8
What is the hallmark feature of acute respiratory distress syndrome (ARDS)?
A) Unilateral pulmonary infiltrates
B) Bilateral infiltrates with decreased pulmonary compliance
C) Bronchial hyperreactivity
D) Elevated pulmonary artery pressure
Rationale: ARDS is defined by bilateral pulmonary infiltrates and reduced lung compliance due
to severe inflammation and fluid accumulation. Unilateral infiltrates, hyperreactivity, or elevated
pressures are not hallmark features.
Question 9
Which type of hypersensitivity reaction is responsible for atopic dermatitis?
A) Type II (cytotoxic)
B) Type I (immediate)
C) Type III (immune complex)
D) Type IV (delayed)
Rationale: Atopic dermatitis is caused by a Type I hypersensitivity reaction involving IgE-
mediated mast cell activation, leading to inflammation and itching. Other types cause different
conditions (e.g., Type IV for contact dermatitis).
Question 10
What is the primary reason X-linked recessive disorders affect males more frequently than
females?
A) Males have two X chromosomes
B) Males have one X chromosome, expressing recessive traits
C) Females lack X chromosomes
D) Males have higher mutation rates
Rationale: Males, with one X and one Y chromosome, express X-linked recessive traits if the
single X carries the mutation. Females, with two X chromosomes, are typically carriers unless
both X chromosomes are affected.
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Question 11
Which cytokine is most responsible for inducing fever during an inflammatory response?
A) Tumor necrosis factor-alpha (TNF-α)
B) Interleukin-1 (IL-1)
C) Interferon-gamma (IFN-γ)
D) Granulocyte-macrophage colony-stimulating factor (GM-CSF)
Rationale: IL-1 is a key pyrogen that acts on the hypothalamus to induce fever. TNF-α
contributes to inflammation, IFN-γ activates macrophages, and GM-CSF stimulates blood cell
production, but they are less directly involved in fever.
Question 12
What is the primary defect in cystic fibrosis?
A) Impaired sodium-potassium ATPase activity
B) Defective CFTR protein function
C) Reduced surfactant production
D) Overactive chloride channels
Rationale: Cystic fibrosis results from mutations in the CFTR gene, leading to defective chloride
transport and thick mucus production. Other options do not describe the primary defect.
Question 13
Which condition results from autoantibodies attacking acetylcholine receptors at the
neuromuscular junction?
A) Myasthenia gravis
B) Multiple sclerosis
C) Guillain-Barré syndrome
D) Amyotrophic lateral sclerosis
Rationale: Myasthenia gravis is caused by autoantibodies blocking acetylcholine receptors,
impairing muscle contraction. Other conditions involve different mechanisms (e.g.,
demyelination in multiple sclerosis).
Question 14
What is the primary cause of metabolic acidosis in diabetic ketoacidosis (DKA)?
A) Hyperventilation
B) Excess ketone body production
C) Loss of bicarbonate in diarrhea
D) Renal retention of chloride
WGU D115 Advanced Pathophysiology
Sample Questions 2025 – 400 Practice
Questions for Units 2–7 with Verified
Answers & Detailed Rationales | A+ Graded
Question 1
Which cells primarily mediate the body's defense against parasitic infections?
A) Neutrophils
B) Eosinophils
C) Basophils
D) Macrophages
Rationale: Eosinophils are specialized for combating parasitic infections, particularly helminths,
by releasing cytotoxic granules. Neutrophils target bacteria, basophils are involved in allergic
responses, and macrophages phagocytose bacteria and debris.
Question 2
What is the primary mechanism by which erythrocytes are destroyed in ABO blood
incompatibility?
A) Direct hemolysis by cytotoxic T cells
B) Activation of the complement pathway
C) Phagocytosis by neutrophils
D) Oxidative stress from reactive oxygen species
Rationale: The complement pathway is activated by antigen-antibody complexes in ABO
incompatibility, leading to erythrocyte lysis. T cells are not primarily involved, neutrophils target
bacteria, and oxidative stress is not the main mechanism.
Question 3
Which characteristic is the most critical determinant of an antigen’s immunogenicity?
A) Molecular weight
B) Ability to be recognized as foreign
C) Chemical composition
D) Solubility in plasma
Rationale: Immunogenicity depends on the immune system recognizing an antigen as foreign,
triggering a response. Molecular weight, composition, and solubility contribute but are secondary
to foreignness.
, 2
Question 4
What is the earliest time frame for detecting HIV infection via RNA testing after sexual
transmission?
A) 1–3 days
B) 4–10 days
C) 11–15 days
D) 16–20 days
Rationale: HIV RNA can be detected 4–10 days post-transmission using nucleic acid
amplification tests, earlier than antibody tests (23–90 days). Testing too soon may yield false
negatives, requiring repeat testing.
Question 5
Which genetic disorder is caused by a deletion on the short arm of chromosome 5, presenting
with a high-pitched, cat-like cry in infancy?
A) Turner syndrome
B) Cri du chat syndrome
C) Down syndrome
D) Klinefelter syndrome
Rationale: Cri du chat syndrome results from a deletion on chromosome 5p, leading to
characteristic features like a cat-like cry, microcephaly, and developmental delays. Other options
involve different chromosomal abnormalities.
Question 6
What is the primary pathophysiological cause of hypertension?
A) Decreased cardiac output
B) Increased cardiac output or peripheral resistance
C) Reduced blood viscosity
D) Impaired baroreceptor function
Rationale: Hypertension is driven by increased cardiac output (e.g., from elevated heart rate or
stroke volume) or increased peripheral resistance (e.g., from vasoconstriction). Reduced
viscosity or baroreceptor issues are not primary causes.
Question 7
Which condition is characterized by a creamy appearance of retinal vessels and serum
triglyceride levels exceeding 2,500 mg/dL?
A) Diabetic retinopathy
B) Hypertriglyceridemia
, 3
C) Hypertensive retinopathy
D) Central retinal vein occlusion
Rationale: Hypertriglyceridemia causes a creamy appearance of retinal vessels (lipemia
retinalis) due to high triglyceride levels. Other conditions affect retinal vessels differently and are
not associated with such triglyceride levels.
Question 8
What is the hallmark feature of acute respiratory distress syndrome (ARDS)?
A) Unilateral pulmonary infiltrates
B) Bilateral infiltrates with decreased pulmonary compliance
C) Bronchial hyperreactivity
D) Elevated pulmonary artery pressure
Rationale: ARDS is defined by bilateral pulmonary infiltrates and reduced lung compliance due
to severe inflammation and fluid accumulation. Unilateral infiltrates, hyperreactivity, or elevated
pressures are not hallmark features.
Question 9
Which type of hypersensitivity reaction is responsible for atopic dermatitis?
A) Type II (cytotoxic)
B) Type I (immediate)
C) Type III (immune complex)
D) Type IV (delayed)
Rationale: Atopic dermatitis is caused by a Type I hypersensitivity reaction involving IgE-
mediated mast cell activation, leading to inflammation and itching. Other types cause different
conditions (e.g., Type IV for contact dermatitis).
Question 10
What is the primary reason X-linked recessive disorders affect males more frequently than
females?
A) Males have two X chromosomes
B) Males have one X chromosome, expressing recessive traits
C) Females lack X chromosomes
D) Males have higher mutation rates
Rationale: Males, with one X and one Y chromosome, express X-linked recessive traits if the
single X carries the mutation. Females, with two X chromosomes, are typically carriers unless
both X chromosomes are affected.
, 4
Question 11
Which cytokine is most responsible for inducing fever during an inflammatory response?
A) Tumor necrosis factor-alpha (TNF-α)
B) Interleukin-1 (IL-1)
C) Interferon-gamma (IFN-γ)
D) Granulocyte-macrophage colony-stimulating factor (GM-CSF)
Rationale: IL-1 is a key pyrogen that acts on the hypothalamus to induce fever. TNF-α
contributes to inflammation, IFN-γ activates macrophages, and GM-CSF stimulates blood cell
production, but they are less directly involved in fever.
Question 12
What is the primary defect in cystic fibrosis?
A) Impaired sodium-potassium ATPase activity
B) Defective CFTR protein function
C) Reduced surfactant production
D) Overactive chloride channels
Rationale: Cystic fibrosis results from mutations in the CFTR gene, leading to defective chloride
transport and thick mucus production. Other options do not describe the primary defect.
Question 13
Which condition results from autoantibodies attacking acetylcholine receptors at the
neuromuscular junction?
A) Myasthenia gravis
B) Multiple sclerosis
C) Guillain-Barré syndrome
D) Amyotrophic lateral sclerosis
Rationale: Myasthenia gravis is caused by autoantibodies blocking acetylcholine receptors,
impairing muscle contraction. Other conditions involve different mechanisms (e.g.,
demyelination in multiple sclerosis).
Question 14
What is the primary cause of metabolic acidosis in diabetic ketoacidosis (DKA)?
A) Hyperventilation
B) Excess ketone body production
C) Loss of bicarbonate in diarrhea
D) Renal retention of chloride
