WCU PHYS 261 MID-TERM EXAM NEWEST 2026
ACTUAL EXAM TEST BANK| PHYS 261 MIDTERM
EXAM REVIEW WITH COMPLETE 400 REAL EXAM
QUESTIONS AND CORRECT VERIFIED ANSWERS/
ALREADY GRADED A+ (MOST RECENT!!)
1. Which organelle is responsible for ATP production via
oxidative phosphorylation?
A) Ribosome
B) Golgi apparatus
C) Mitochondrion
D) Lysosome
Correct Answer: C) Mitochondrion
Rationale: Mitochondria are the "powerhouses" of the cell,
producing ATP through the electron transport chain and oxidative
phosphorylation.
2. Which transport process requires a carrier protein but does
NOT require direct ATP hydrolysis?
A) Primary active transport
B) Facilitated diffusion
1
, C) Simple diffusion
D) Endocytosis
Correct Answer: B) Facilitated diffusion
Rationale: Facilitated diffusion uses carrier or channel proteins to
move substances down their concentration gradient without direct
ATP use.
3. The sodium-potassium pump (Na⁺/K⁺-ATPase) transports:
A) 2 Na⁺ out, 3 K⁺ in
B) 3 Na⁺ out, 2 K⁺ in
C) 1 Na⁺ out, 1 K⁺ in
D) 3 Na⁺ in, 2 K⁺ out
Correct Answer: B) 3 Na⁺ out, 2 K⁺ in
Rationale: The pump maintains the resting membrane potential
by exporting 3 sodium ions and importing 2 potassium ions per
ATP hydrolyzed.
4. If a cell is placed in a hypertonic solution, the cell will:
A) Swell and possibly burst
B) Shrink (crenate)
2
, C) Remain unchanged
D) Actively transport water in
Correct Answer: B) Shrink (crenate)
Rationale: Water moves out of the cell into the hypertonic
extracellular fluid by osmosis, causing cell shrinkage.
5. The resting membrane potential of a typical neuron is
approximately:
A) –70 mV
B) +30 mV
C) 0 mV
D) –90 mV
Correct Answer: A) –70 mV
Rationale: The resting membrane potential is maintained by the
Na⁺/K⁺ pump and potassium leak channels, with the inside
negative relative to the outside.
6. Which ion has the highest permeability at rest in a neuron?
A) Sodium (Na⁺)
B) Potassium (K⁺)
3
, C) Calcium (Ca²⁺)
D) Chloride (Cl⁻)
Correct Answer: B) Potassium (K⁺)
Rationale: At rest, potassium leak channels are open, making K⁺
the most permeable ion and the primary contributor to resting
membrane potential.
7. Which phase of an action potential is caused by the opening
of voltage-gated sodium channels?
A) Depolarization (rising phase)
B) Repolarization
C) Hyperpolarization
D) After-hyperpolarization
Correct Answer: A) Depolarization (rising phase)
Rationale: Influx of Na⁺ through voltage-gated Na⁺ channels
causes membrane potential to become positive (depolarization).
8. Repolarization of a neuron occurs due to:
A) Opening of voltage-gated K⁺ channels and closing of
Na⁺ channels
4
ACTUAL EXAM TEST BANK| PHYS 261 MIDTERM
EXAM REVIEW WITH COMPLETE 400 REAL EXAM
QUESTIONS AND CORRECT VERIFIED ANSWERS/
ALREADY GRADED A+ (MOST RECENT!!)
1. Which organelle is responsible for ATP production via
oxidative phosphorylation?
A) Ribosome
B) Golgi apparatus
C) Mitochondrion
D) Lysosome
Correct Answer: C) Mitochondrion
Rationale: Mitochondria are the "powerhouses" of the cell,
producing ATP through the electron transport chain and oxidative
phosphorylation.
2. Which transport process requires a carrier protein but does
NOT require direct ATP hydrolysis?
A) Primary active transport
B) Facilitated diffusion
1
, C) Simple diffusion
D) Endocytosis
Correct Answer: B) Facilitated diffusion
Rationale: Facilitated diffusion uses carrier or channel proteins to
move substances down their concentration gradient without direct
ATP use.
3. The sodium-potassium pump (Na⁺/K⁺-ATPase) transports:
A) 2 Na⁺ out, 3 K⁺ in
B) 3 Na⁺ out, 2 K⁺ in
C) 1 Na⁺ out, 1 K⁺ in
D) 3 Na⁺ in, 2 K⁺ out
Correct Answer: B) 3 Na⁺ out, 2 K⁺ in
Rationale: The pump maintains the resting membrane potential
by exporting 3 sodium ions and importing 2 potassium ions per
ATP hydrolyzed.
4. If a cell is placed in a hypertonic solution, the cell will:
A) Swell and possibly burst
B) Shrink (crenate)
2
, C) Remain unchanged
D) Actively transport water in
Correct Answer: B) Shrink (crenate)
Rationale: Water moves out of the cell into the hypertonic
extracellular fluid by osmosis, causing cell shrinkage.
5. The resting membrane potential of a typical neuron is
approximately:
A) –70 mV
B) +30 mV
C) 0 mV
D) –90 mV
Correct Answer: A) –70 mV
Rationale: The resting membrane potential is maintained by the
Na⁺/K⁺ pump and potassium leak channels, with the inside
negative relative to the outside.
6. Which ion has the highest permeability at rest in a neuron?
A) Sodium (Na⁺)
B) Potassium (K⁺)
3
, C) Calcium (Ca²⁺)
D) Chloride (Cl⁻)
Correct Answer: B) Potassium (K⁺)
Rationale: At rest, potassium leak channels are open, making K⁺
the most permeable ion and the primary contributor to resting
membrane potential.
7. Which phase of an action potential is caused by the opening
of voltage-gated sodium channels?
A) Depolarization (rising phase)
B) Repolarization
C) Hyperpolarization
D) After-hyperpolarization
Correct Answer: A) Depolarization (rising phase)
Rationale: Influx of Na⁺ through voltage-gated Na⁺ channels
causes membrane potential to become positive (depolarization).
8. Repolarization of a neuron occurs due to:
A) Opening of voltage-gated K⁺ channels and closing of
Na⁺ channels
4
