Human Physiology Exam Test Bank 2026/2027 |
200 Q&As with Rationales | Graded A+ Ultimate
Study Guide
Question 1
An experimental drug blocks the activity of the sodium-potassium pump (
Na+/K+cap N a raised to the positive power / cap K raised to the positive power
𝑁𝑎+/𝐾+
ATPase). What is the immediate direct consequence on the intracellular
concentrations of sodium and potassium?
A) Intracellular sodium decreases; intracellular potassium increases.
B) Intracellular sodium increases; intracellular potassium decreases.
,C) Both sodium and potassium accumulate inside the cell.
D) Both sodium and potassium deplete from the cell.
Verified Answer: B
Explanation: The
Na+/K+cap N a raised to the positive power / cap K raised to the positive power
𝑁𝑎+/𝐾+
ATPase actively pumps 3 sodium ions out of the cell and 2 potassium ions into the
cell per ATP molecule hydrolyzed. Inhibiting this primary active transporter halts
this process, causing sodium to build up inside the cell while potassium leaks out
and falls below normal intracellular levels.
Question 2
A red blood cell is placed in an unknown solution and immediately begins to shrink
and undergo crenation. How should this external solution be classified relative to the
cell’s cytoplasm?
A) Hypotonic
B) Isotonic
C) Hypertonic
D) Iso-osmotic but hypotonic
Verified Answer: C
Explanation: A hypertonic solution contains a higher concentration of non-
penetrating solutes than the intracellular environment. This concentration gradient
forces water to passively exit the cell via osmosis down its concentration gradient,
leading to cell shrinkage and crenation.
Question 3
Which of the following transport mechanisms requires a specific membrane carrier
protein but does not utilize chemical energy (ATP) directly or indirectly?
A) Simple diffusion
B) Facilitated diffusion
C) Primary active transport
D) Secondary active transport
,Verified Answer: B
Explanation: Facilitated diffusion is a type of passive transport that utilizes selective
transmembrane carrier proteins or channels to move substances down their
electrochemical gradients. Because movement is downhill, it requires no cellular
metabolic energy.
Question 4
During the upstroke (Phase 0) of a typical neuronal action potential, which channel
gate configuration change occurs rapidly at the threshold voltage?
A) Opening of the activation gates of voltage-gated
K+cap K raised to the positive power
𝐾+
channels
B) Closing of the inactivation gates of voltage-gated
Na+cap N a raised to the positive power
𝑁𝑎+
channels
C) Opening of the activation gates of voltage-gated
Na+cap N a raised to the positive power
𝑁𝑎+
channels
D) Activation of ligand-gated chloride channels
Verified Answer: C
Explanation: Reaching threshold potential triggers the rapid opening of the
activation gates of voltage-gated fast
Na+cap N a raised to the positive power
, 𝑁𝑎+
channels. This produces a massive inward current of sodium ions, driving the
membrane potential toward the sodium equilibrium potential.
Question 5
What is the structural purpose of the tight junctions (zonula occludens) located
between adjacent epithelial cells in the intestinal mucosa?
A) To facilitate rapid electrical coupling via gap junctions
B) To anchor cells firmly to the underlying basement membrane
C) To restrict paracellular transport and maintain cell polarity
D) To enable bulk endocytosis across the apical membrane
Verified Answer: C
Explanation: Tight junctions form a selective, seal-like barrier between neighboring
epithelial cells. This configuration limits the un-regulated paracellular movement of
solutes and water, forcing nutrients to pass through transcellular pathways while
separating apical and basolateral proteins.
Question 6
A mutation in the gene encoding the cystic fibrosis transmembrane conductance
regulator (CFTR) disrupts the transport of which ion across epithelial membranes?
A) Sodium
B) Potassium
C) Chloride
D) Calcium
Verified Answer: C
Explanation: The CFTR protein is an ATP-gated, cAMP-regulated chloride
channel. Mutations in this gene impair chloride secretion out of epithelial cells into
the lumen, which decreases water secretion and yields abnormally thick, viscous
mucus in respiratory and GI tracts.
Question 7
How does an increase in the extracellular concentration of potassium ions affect the
resting membrane potential of a standard excitable cell?
A) Hyperpolarizes the membrane potential
200 Q&As with Rationales | Graded A+ Ultimate
Study Guide
Question 1
An experimental drug blocks the activity of the sodium-potassium pump (
Na+/K+cap N a raised to the positive power / cap K raised to the positive power
𝑁𝑎+/𝐾+
ATPase). What is the immediate direct consequence on the intracellular
concentrations of sodium and potassium?
A) Intracellular sodium decreases; intracellular potassium increases.
B) Intracellular sodium increases; intracellular potassium decreases.
,C) Both sodium and potassium accumulate inside the cell.
D) Both sodium and potassium deplete from the cell.
Verified Answer: B
Explanation: The
Na+/K+cap N a raised to the positive power / cap K raised to the positive power
𝑁𝑎+/𝐾+
ATPase actively pumps 3 sodium ions out of the cell and 2 potassium ions into the
cell per ATP molecule hydrolyzed. Inhibiting this primary active transporter halts
this process, causing sodium to build up inside the cell while potassium leaks out
and falls below normal intracellular levels.
Question 2
A red blood cell is placed in an unknown solution and immediately begins to shrink
and undergo crenation. How should this external solution be classified relative to the
cell’s cytoplasm?
A) Hypotonic
B) Isotonic
C) Hypertonic
D) Iso-osmotic but hypotonic
Verified Answer: C
Explanation: A hypertonic solution contains a higher concentration of non-
penetrating solutes than the intracellular environment. This concentration gradient
forces water to passively exit the cell via osmosis down its concentration gradient,
leading to cell shrinkage and crenation.
Question 3
Which of the following transport mechanisms requires a specific membrane carrier
protein but does not utilize chemical energy (ATP) directly or indirectly?
A) Simple diffusion
B) Facilitated diffusion
C) Primary active transport
D) Secondary active transport
,Verified Answer: B
Explanation: Facilitated diffusion is a type of passive transport that utilizes selective
transmembrane carrier proteins or channels to move substances down their
electrochemical gradients. Because movement is downhill, it requires no cellular
metabolic energy.
Question 4
During the upstroke (Phase 0) of a typical neuronal action potential, which channel
gate configuration change occurs rapidly at the threshold voltage?
A) Opening of the activation gates of voltage-gated
K+cap K raised to the positive power
𝐾+
channels
B) Closing of the inactivation gates of voltage-gated
Na+cap N a raised to the positive power
𝑁𝑎+
channels
C) Opening of the activation gates of voltage-gated
Na+cap N a raised to the positive power
𝑁𝑎+
channels
D) Activation of ligand-gated chloride channels
Verified Answer: C
Explanation: Reaching threshold potential triggers the rapid opening of the
activation gates of voltage-gated fast
Na+cap N a raised to the positive power
, 𝑁𝑎+
channels. This produces a massive inward current of sodium ions, driving the
membrane potential toward the sodium equilibrium potential.
Question 5
What is the structural purpose of the tight junctions (zonula occludens) located
between adjacent epithelial cells in the intestinal mucosa?
A) To facilitate rapid electrical coupling via gap junctions
B) To anchor cells firmly to the underlying basement membrane
C) To restrict paracellular transport and maintain cell polarity
D) To enable bulk endocytosis across the apical membrane
Verified Answer: C
Explanation: Tight junctions form a selective, seal-like barrier between neighboring
epithelial cells. This configuration limits the un-regulated paracellular movement of
solutes and water, forcing nutrients to pass through transcellular pathways while
separating apical and basolateral proteins.
Question 6
A mutation in the gene encoding the cystic fibrosis transmembrane conductance
regulator (CFTR) disrupts the transport of which ion across epithelial membranes?
A) Sodium
B) Potassium
C) Chloride
D) Calcium
Verified Answer: C
Explanation: The CFTR protein is an ATP-gated, cAMP-regulated chloride
channel. Mutations in this gene impair chloride secretion out of epithelial cells into
the lumen, which decreases water secretion and yields abnormally thick, viscous
mucus in respiratory and GI tracts.
Question 7
How does an increase in the extracellular concentration of potassium ions affect the
resting membrane potential of a standard excitable cell?
A) Hyperpolarizes the membrane potential
