WGU D313 ANATOMY AND PHYSIOLOGY
II GUIDE CURRENTLY TESTING EXAM 300
QUESTIONS WITH DETAILED VERIFIED
ANSWERS WITH RATIONALES (100% CORRECT
ANSWERS /ALREADY GRADED
Topics systematically progress through cardiovascular hemodynamics, respiratory
gas exchange, renal filtration and acid-base balance, digestive enzyme function,
endocrine feedback loops, reproductive biology, and immune responses. This
resource is designed to mimic the depth and style of WGU objective assessments,
ensuring thorough preparation for the course and the OA.
1. What is the primary pacemaker of the heart?
A) Atrioventricular node
B) Purkinje fibers
C) Sinoatrial node
D) Bundle of His
Correct: C
Rationale: The sinoatrial node generates action potentials at the highest intrinsic
rate (60-100 bpm) and drives the entire cardiac cycle, making it the primary
pacemaker. The AV node has a slower rate and serves as a backup.
2. Which valve prevents backflow from the left ventricle into the left atrium?
A) Aortic valve
B) Pulmonary valve
C) Tricuspid valve
1
,D) Mitral valve
Correct: D
Rationale: The mitral (bicuspid) valve has two cusps and closes during ventricular
systole. Its leaflets are anchored by chordae tendineae to prevent prolapse and
retrograde flow into the left atrium.
3. What is the average resting cardiac output for an adult?
A) 2.5 L/min
B) 5.0 L/min
C) 7.5 L/min
D) 10.0 L/min
Correct: B
Rationale: Cardiac output = heart rate (≈70 bpm) × stroke volume (≈70 mL) =
4,900 mL/min or ~5 L/min. This matches total blood volume circulating each
minute at rest.
4. Which vessel wall layer mediates vasoconstriction?
A) Tunica intima
B) Tunica media
C) Tunica externa
D) Endothelium
Correct: B
Rationale: The tunica media contains smooth muscle innervated by sympathetic
fibers. Its contraction reduces vessel diameter and increases resistance, while
relaxation decreases resistance.
5. What is the function of the chordae tendineae?
2
,A) Generate electrical impulses for heart contraction
B) Anchor atrioventricular valve cusps to papillary muscles
C) Dilate coronary arteries during exercise
D) Regulate blood viscosity in the ventricles
Correct: B
Rationale: Chordae tendineae are fibrous cords that attach to the mitral and
tricuspid valve leaflets. They prevent valve prolapse into the atria during
ventricular systole, ensuring one-way blood flow.
6. Where does the majority of nutrient absorption occur?
A) Stomach
B) Large intestine
C) Small intestine
D) Esophagus
Correct: C
Rationale: The small intestine has circular folds, villi, and microvilli that
dramatically increase surface area. It absorbs carbohydrates, proteins, lipids,
vitamins, and minerals, with different segments specializing in specific nutrients.
7. Which enzyme initiates protein digestion in the stomach?
A) Amylase
B) Lipase
C) Pepsin
D) Trypsin
Correct: C
3
, Rationale: Pepsin is secreted as inactive pepsinogen by chief cells and activated by
hydrochloric acid. It cleaves peptide bonds near aromatic amino acids, beginning
the breakdown of dietary proteins into polypeptides.
8. What is the primary site of hematopoiesis in adults?
A) Liver
B) Spleen
C) Red bone marrow
D) Thymus
Correct: C
Rationale: Red bone marrow in flat bones (sternum, pelvis, ribs, vertebrae)
contains hematopoietic stem cells that differentiate into erythrocytes, leukocytes,
and thrombocytes. The liver and spleen are active in fetal life but not in adult
hematopoiesis.
9. Which hormone stimulates red blood cell production?
A) Thyroxine
B) Erythropoietin
C) Aldosterone
D) Cortisol
Correct: B
Rationale: Erythropoietin is produced by the kidneys in response to hypoxia. It
binds to receptors on erythroid progenitor cells in bone marrow, increasing
erythropoiesis and oxygen-carrying capacity.
10. What is the functional unit of the kidney?
A) Renal pyramid
B) Nephron
4
II GUIDE CURRENTLY TESTING EXAM 300
QUESTIONS WITH DETAILED VERIFIED
ANSWERS WITH RATIONALES (100% CORRECT
ANSWERS /ALREADY GRADED
Topics systematically progress through cardiovascular hemodynamics, respiratory
gas exchange, renal filtration and acid-base balance, digestive enzyme function,
endocrine feedback loops, reproductive biology, and immune responses. This
resource is designed to mimic the depth and style of WGU objective assessments,
ensuring thorough preparation for the course and the OA.
1. What is the primary pacemaker of the heart?
A) Atrioventricular node
B) Purkinje fibers
C) Sinoatrial node
D) Bundle of His
Correct: C
Rationale: The sinoatrial node generates action potentials at the highest intrinsic
rate (60-100 bpm) and drives the entire cardiac cycle, making it the primary
pacemaker. The AV node has a slower rate and serves as a backup.
2. Which valve prevents backflow from the left ventricle into the left atrium?
A) Aortic valve
B) Pulmonary valve
C) Tricuspid valve
1
,D) Mitral valve
Correct: D
Rationale: The mitral (bicuspid) valve has two cusps and closes during ventricular
systole. Its leaflets are anchored by chordae tendineae to prevent prolapse and
retrograde flow into the left atrium.
3. What is the average resting cardiac output for an adult?
A) 2.5 L/min
B) 5.0 L/min
C) 7.5 L/min
D) 10.0 L/min
Correct: B
Rationale: Cardiac output = heart rate (≈70 bpm) × stroke volume (≈70 mL) =
4,900 mL/min or ~5 L/min. This matches total blood volume circulating each
minute at rest.
4. Which vessel wall layer mediates vasoconstriction?
A) Tunica intima
B) Tunica media
C) Tunica externa
D) Endothelium
Correct: B
Rationale: The tunica media contains smooth muscle innervated by sympathetic
fibers. Its contraction reduces vessel diameter and increases resistance, while
relaxation decreases resistance.
5. What is the function of the chordae tendineae?
2
,A) Generate electrical impulses for heart contraction
B) Anchor atrioventricular valve cusps to papillary muscles
C) Dilate coronary arteries during exercise
D) Regulate blood viscosity in the ventricles
Correct: B
Rationale: Chordae tendineae are fibrous cords that attach to the mitral and
tricuspid valve leaflets. They prevent valve prolapse into the atria during
ventricular systole, ensuring one-way blood flow.
6. Where does the majority of nutrient absorption occur?
A) Stomach
B) Large intestine
C) Small intestine
D) Esophagus
Correct: C
Rationale: The small intestine has circular folds, villi, and microvilli that
dramatically increase surface area. It absorbs carbohydrates, proteins, lipids,
vitamins, and minerals, with different segments specializing in specific nutrients.
7. Which enzyme initiates protein digestion in the stomach?
A) Amylase
B) Lipase
C) Pepsin
D) Trypsin
Correct: C
3
, Rationale: Pepsin is secreted as inactive pepsinogen by chief cells and activated by
hydrochloric acid. It cleaves peptide bonds near aromatic amino acids, beginning
the breakdown of dietary proteins into polypeptides.
8. What is the primary site of hematopoiesis in adults?
A) Liver
B) Spleen
C) Red bone marrow
D) Thymus
Correct: C
Rationale: Red bone marrow in flat bones (sternum, pelvis, ribs, vertebrae)
contains hematopoietic stem cells that differentiate into erythrocytes, leukocytes,
and thrombocytes. The liver and spleen are active in fetal life but not in adult
hematopoiesis.
9. Which hormone stimulates red blood cell production?
A) Thyroxine
B) Erythropoietin
C) Aldosterone
D) Cortisol
Correct: B
Rationale: Erythropoietin is produced by the kidneys in response to hypoxia. It
binds to receptors on erythroid progenitor cells in bone marrow, increasing
erythropoiesis and oxygen-carrying capacity.
10. What is the functional unit of the kidney?
A) Renal pyramid
B) Nephron
4
