APHY 101 Exam Practice Questions and Correct
Answers Latest
Question 1: Which of the following best describes the primary function of the sodium-
potassium pump in maintaining the resting membrane potential of a neuron?
A. It allows sodium ions to passively diffuse into the cell, depolarizing the membrane.
B. It actively transports three potassium ions into the cell for every two sodium ions out,
contributing to a negative intracellular charge.
C. It actively transports three sodium ions out of the cell for every two potassium ions in,
contributing to a negative intracellular charge.
D. It facilitates the exchange of chloride and bicarbonate ions to regulate pH.
CORRECT ANSWER: C. It actively transports three sodium ions out of the cell for every two
potassium ions in, contributing to a negative intracellular charge.
Rationale: The Na+/K+ ATPase pump is a critical active transport mechanism that moves 3 Na+
ions out of the cell and 2 K+ ions into the cell per ATP hydrolyzed. This creates both a
concentration gradient and an electrical gradient (more positive charges outside than inside),
which is fundamental to establishing the negative resting membrane potential (~-70mV)
essential for neuronal excitability. Option B reverses the ion ratio, while A and D describe
passive or unrelated transport mechanisms.
Question 2: During skeletal muscle contraction, what is the direct role of calcium ions (Ca²⁺)
released from the sarcoplasmic reticulum?
A. To bind to troponin, causing a conformational change that moves tropomyosin away from
actin's myosin-binding sites.
B. To directly power the myosin head's power stroke by hydrolyzing ATP.
C. To depolarize the sarcolemma and trigger an action potential along the T-tubule.
D. To bind to myosin, increasing its affinity for actin.
CORRECT ANSWER: A. To bind to troponin, causing a conformational change that moves
tropomyosin away from actin's myosin-binding sites.
Rationale: In the excitation-contraction coupling process, Ca²⁺ release is the key trigger. Ca²⁺
binds to the troponin complex on the thin filament, causing tropomyosin to shift position and
expose the myosin-binding sites on actin. This allows cross-bridge cycling to begin. Option B
describes the role of ATP hydrolysis by myosin ATPase. Option C describes the initial event
,(action potential propagation), not Ca²⁺'s direct role. Option D is incorrect; Ca²⁺ acts via
troponin, not directly on myosin.
Question 3: A patient presents with a fracture of the surgical neck of the humerus. Which
nerve is most at risk for injury in this scenario, potentially leading to weakness in shoulder
abduction and loss of sensation over the lateral deltoid?
A. Radial nerve
B. Median nerve
C. Ulnar nerve
D. Axillary nerve
CORRECT ANSWER: D. Axillary nerve
Rationale: The axillary nerve (C5-C6) wraps around the surgical neck of the humerus and
innervates the deltoid (primary shoulder abductor) and teres minor muscles, as well as
providing sensory innervation to the regimental badge area (lateral shoulder). A fracture at the
surgical neck can directly damage this nerve. The radial nerve is more commonly injured in mid-
shaft humeral fractures, while the median and ulnar nerves are primarily associated with
forearm and hand injuries.
Question 4: Which of the following statements accurately describes the difference between
endocrine and exocrine glands?
A. Endocrine glands secrete hormones into ducts, while exocrine glands secrete directly into the
bloodstream.
B. Endocrine glands are ductless and secrete hormones directly into the bloodstream or
interstitial fluid, while exocrine glands secrete products onto epithelial surfaces via ducts.
C. Endocrine glands only secrete proteins, while exocrine glands only secrete lipids.
D. Endocrine glands are found only in the brain, while exocrine glands are found throughout the
body.
CORRECT ANSWER: B. Endocrine glands are ductless and secrete hormones directly into the
bloodstream or interstitial fluid, while exocrine glands secrete products onto epithelial
surfaces via ducts.
Rationale: This is the fundamental histological and functional distinction. Endocrine glands (e.g.,
pituitary, thyroid) release hormones into the blood for systemic effects. Exocrine glands (e.g.,
salivary, sweat, pancreatic acini) use ducts to deliver secretions (enzymes, mucus, sweat) to
specific locations like the skin surface or body cavities. Options A, C, and D contain significant
factual errors regarding secretion pathways, product types, and anatomical distribution.
,Question 5: In the renal nephron, where does the majority of glucose reabsorption occur
under normal physiological conditions?
A. Proximal convoluted tubule (PCT)
B. Loop of Henle
C. Distal convoluted tubule (DCT)
D. Collecting duct
CORRECT ANSWER: A. Proximal convoluted tubule (PCT)
Rationale: The PCT is responsible for reabsorbing approximately 65-70% of filtered water,
sodium, and virtually 100% of filtered glucose and amino acids via active transport and co-
transport mechanisms (e.g., SGLT transporters). The Loop of Henle primarily concentrates urine
via countercurrent multiplication. The DCT and collecting duct fine-tune electrolyte and water
balance under hormonal control (aldosterone, ADH) but do not significantly reabsorb glucose.
Question 6: Which of the following best describes the function of surfactant produced by
type II alveolar cells in the lungs?
A. To increase surface tension within the alveoli, preventing collapse during expiration.
B. To decrease surface tension within the alveoli, preventing collapse during expiration and
reducing the work of breathing.
C. To trap inhaled pathogens and facilitate their removal by ciliary action.
D. To serve as the primary site for gas exchange between air and blood.
CORRECT ANSWER: B. To decrease surface tension within the alveoli, preventing collapse
during expiration and reducing the work of breathing.
Rationale: Pulmonary surfactant, a phospholipid-protein complex, reduces alveolar surface
tension according to the Law of Laplace (P=2T/r). By lowering tension (T), it prevents small
alveoli from collapsing into larger ones (atelectasis) during expiration and significantly decreases
the effort required to inflate the lungs. Option A is the opposite of surfactant's true function.
Option C describes mucus and the mucociliary escalator. Option D describes the function of the
alveolar-capillary membrane itself.
Question 7: During the cardiac cycle, the "lub" sound (S1) is primarily caused by:
A. The closure of the aortic and pulmonary valves at the beginning of ventricular diastole.
B. The closure of the atrioventricular (mitral and tricuspid) valves at the beginning of ventricular
systole.
C. The rapid filling of the ventricles during early diastole.
D. The contraction of the atria during atrial systole.
, CORRECT ANSWER: B. The closure of the atrioventricular (mitral and tricuspid) valves at the
beginning of ventricular systole.
Rationale: S1 marks the onset of ventricular systole (isovolumetric contraction). The rising
ventricular pressure causes the mitral and tricuspid valves to snap shut, producing the "lub"
sound. S2 ("dub") is caused by closure of the semilunar valves (aortic/pulmonary) at the start of
ventricular diastole. Options C and D describe events that do not produce the primary heart
sounds.
Question 8: Which hormone, secreted by the posterior pituitary gland, plays a key role in
water conservation by increasing the permeability of the collecting ducts in the kidney to
water?
A. Aldosterone
B. Antidiuretic hormone (ADH, or vasopressin)
C. Atrial natriuretic peptide (ANP)
D. Renin
CORRECT ANSWER: B. Antidiuretic hormone (ADH, or vasopressin)
Rationale: ADH is synthesized in the hypothalamus and stored/released from the posterior
pituitary. It acts on the collecting ducts of the nephron to insert aquaporin-2 channels into the
apical membrane, allowing water reabsorption down its osmotic gradient, thus concentrating
urine and conserving body water. Aldosterone (A) acts on the DCT/collecting duct to increase
Na+ reabsorption (and thus water follows passively). ANP (C) promotes Na+ and water
excretion. Renin (D) is an enzyme from the kidney that initiates the RAAS pathway.
Question 9: In a negative feedback loop regulating blood glucose levels, what is the role of
insulin secreted by pancreatic beta cells?
A. To stimulate glycogenolysis and gluconeogenesis in the liver, raising blood glucose.
B. To facilitate the uptake of glucose into cells (especially muscle and adipose) and promote
glycogen synthesis, lowering blood glucose.
C. To inhibit the secretion of glucagon from pancreatic alpha cells.
D. To increase the breakdown of triglycerides into free fatty acids for energy.
CORRECT ANSWER: B. To facilitate the uptake of glucose into cells (especially muscle and
adipose) and promote glycogen synthesis, lowering blood glucose.
Rationale: Insulin is the primary anabolic hormone for glucose homeostasis. It lowers blood
glucose by promoting cellular uptake (via GLUT4 translocation), glycogen synthesis
(glycogenesis) in liver and muscle, and inhibiting gluconeogenesis/glycogenolysis. Option A
Answers Latest
Question 1: Which of the following best describes the primary function of the sodium-
potassium pump in maintaining the resting membrane potential of a neuron?
A. It allows sodium ions to passively diffuse into the cell, depolarizing the membrane.
B. It actively transports three potassium ions into the cell for every two sodium ions out,
contributing to a negative intracellular charge.
C. It actively transports three sodium ions out of the cell for every two potassium ions in,
contributing to a negative intracellular charge.
D. It facilitates the exchange of chloride and bicarbonate ions to regulate pH.
CORRECT ANSWER: C. It actively transports three sodium ions out of the cell for every two
potassium ions in, contributing to a negative intracellular charge.
Rationale: The Na+/K+ ATPase pump is a critical active transport mechanism that moves 3 Na+
ions out of the cell and 2 K+ ions into the cell per ATP hydrolyzed. This creates both a
concentration gradient and an electrical gradient (more positive charges outside than inside),
which is fundamental to establishing the negative resting membrane potential (~-70mV)
essential for neuronal excitability. Option B reverses the ion ratio, while A and D describe
passive or unrelated transport mechanisms.
Question 2: During skeletal muscle contraction, what is the direct role of calcium ions (Ca²⁺)
released from the sarcoplasmic reticulum?
A. To bind to troponin, causing a conformational change that moves tropomyosin away from
actin's myosin-binding sites.
B. To directly power the myosin head's power stroke by hydrolyzing ATP.
C. To depolarize the sarcolemma and trigger an action potential along the T-tubule.
D. To bind to myosin, increasing its affinity for actin.
CORRECT ANSWER: A. To bind to troponin, causing a conformational change that moves
tropomyosin away from actin's myosin-binding sites.
Rationale: In the excitation-contraction coupling process, Ca²⁺ release is the key trigger. Ca²⁺
binds to the troponin complex on the thin filament, causing tropomyosin to shift position and
expose the myosin-binding sites on actin. This allows cross-bridge cycling to begin. Option B
describes the role of ATP hydrolysis by myosin ATPase. Option C describes the initial event
,(action potential propagation), not Ca²⁺'s direct role. Option D is incorrect; Ca²⁺ acts via
troponin, not directly on myosin.
Question 3: A patient presents with a fracture of the surgical neck of the humerus. Which
nerve is most at risk for injury in this scenario, potentially leading to weakness in shoulder
abduction and loss of sensation over the lateral deltoid?
A. Radial nerve
B. Median nerve
C. Ulnar nerve
D. Axillary nerve
CORRECT ANSWER: D. Axillary nerve
Rationale: The axillary nerve (C5-C6) wraps around the surgical neck of the humerus and
innervates the deltoid (primary shoulder abductor) and teres minor muscles, as well as
providing sensory innervation to the regimental badge area (lateral shoulder). A fracture at the
surgical neck can directly damage this nerve. The radial nerve is more commonly injured in mid-
shaft humeral fractures, while the median and ulnar nerves are primarily associated with
forearm and hand injuries.
Question 4: Which of the following statements accurately describes the difference between
endocrine and exocrine glands?
A. Endocrine glands secrete hormones into ducts, while exocrine glands secrete directly into the
bloodstream.
B. Endocrine glands are ductless and secrete hormones directly into the bloodstream or
interstitial fluid, while exocrine glands secrete products onto epithelial surfaces via ducts.
C. Endocrine glands only secrete proteins, while exocrine glands only secrete lipids.
D. Endocrine glands are found only in the brain, while exocrine glands are found throughout the
body.
CORRECT ANSWER: B. Endocrine glands are ductless and secrete hormones directly into the
bloodstream or interstitial fluid, while exocrine glands secrete products onto epithelial
surfaces via ducts.
Rationale: This is the fundamental histological and functional distinction. Endocrine glands (e.g.,
pituitary, thyroid) release hormones into the blood for systemic effects. Exocrine glands (e.g.,
salivary, sweat, pancreatic acini) use ducts to deliver secretions (enzymes, mucus, sweat) to
specific locations like the skin surface or body cavities. Options A, C, and D contain significant
factual errors regarding secretion pathways, product types, and anatomical distribution.
,Question 5: In the renal nephron, where does the majority of glucose reabsorption occur
under normal physiological conditions?
A. Proximal convoluted tubule (PCT)
B. Loop of Henle
C. Distal convoluted tubule (DCT)
D. Collecting duct
CORRECT ANSWER: A. Proximal convoluted tubule (PCT)
Rationale: The PCT is responsible for reabsorbing approximately 65-70% of filtered water,
sodium, and virtually 100% of filtered glucose and amino acids via active transport and co-
transport mechanisms (e.g., SGLT transporters). The Loop of Henle primarily concentrates urine
via countercurrent multiplication. The DCT and collecting duct fine-tune electrolyte and water
balance under hormonal control (aldosterone, ADH) but do not significantly reabsorb glucose.
Question 6: Which of the following best describes the function of surfactant produced by
type II alveolar cells in the lungs?
A. To increase surface tension within the alveoli, preventing collapse during expiration.
B. To decrease surface tension within the alveoli, preventing collapse during expiration and
reducing the work of breathing.
C. To trap inhaled pathogens and facilitate their removal by ciliary action.
D. To serve as the primary site for gas exchange between air and blood.
CORRECT ANSWER: B. To decrease surface tension within the alveoli, preventing collapse
during expiration and reducing the work of breathing.
Rationale: Pulmonary surfactant, a phospholipid-protein complex, reduces alveolar surface
tension according to the Law of Laplace (P=2T/r). By lowering tension (T), it prevents small
alveoli from collapsing into larger ones (atelectasis) during expiration and significantly decreases
the effort required to inflate the lungs. Option A is the opposite of surfactant's true function.
Option C describes mucus and the mucociliary escalator. Option D describes the function of the
alveolar-capillary membrane itself.
Question 7: During the cardiac cycle, the "lub" sound (S1) is primarily caused by:
A. The closure of the aortic and pulmonary valves at the beginning of ventricular diastole.
B. The closure of the atrioventricular (mitral and tricuspid) valves at the beginning of ventricular
systole.
C. The rapid filling of the ventricles during early diastole.
D. The contraction of the atria during atrial systole.
, CORRECT ANSWER: B. The closure of the atrioventricular (mitral and tricuspid) valves at the
beginning of ventricular systole.
Rationale: S1 marks the onset of ventricular systole (isovolumetric contraction). The rising
ventricular pressure causes the mitral and tricuspid valves to snap shut, producing the "lub"
sound. S2 ("dub") is caused by closure of the semilunar valves (aortic/pulmonary) at the start of
ventricular diastole. Options C and D describe events that do not produce the primary heart
sounds.
Question 8: Which hormone, secreted by the posterior pituitary gland, plays a key role in
water conservation by increasing the permeability of the collecting ducts in the kidney to
water?
A. Aldosterone
B. Antidiuretic hormone (ADH, or vasopressin)
C. Atrial natriuretic peptide (ANP)
D. Renin
CORRECT ANSWER: B. Antidiuretic hormone (ADH, or vasopressin)
Rationale: ADH is synthesized in the hypothalamus and stored/released from the posterior
pituitary. It acts on the collecting ducts of the nephron to insert aquaporin-2 channels into the
apical membrane, allowing water reabsorption down its osmotic gradient, thus concentrating
urine and conserving body water. Aldosterone (A) acts on the DCT/collecting duct to increase
Na+ reabsorption (and thus water follows passively). ANP (C) promotes Na+ and water
excretion. Renin (D) is an enzyme from the kidney that initiates the RAAS pathway.
Question 9: In a negative feedback loop regulating blood glucose levels, what is the role of
insulin secreted by pancreatic beta cells?
A. To stimulate glycogenolysis and gluconeogenesis in the liver, raising blood glucose.
B. To facilitate the uptake of glucose into cells (especially muscle and adipose) and promote
glycogen synthesis, lowering blood glucose.
C. To inhibit the secretion of glucagon from pancreatic alpha cells.
D. To increase the breakdown of triglycerides into free fatty acids for energy.
CORRECT ANSWER: B. To facilitate the uptake of glucose into cells (especially muscle and
adipose) and promote glycogen synthesis, lowering blood glucose.
Rationale: Insulin is the primary anabolic hormone for glucose homeostasis. It lowers blood
glucose by promoting cellular uptake (via GLUT4 translocation), glycogen synthesis
(glycogenesis) in liver and muscle, and inhibiting gluconeogenesis/glycogenolysis. Option A
