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IBHRE ACTUAL EXAM PAPER 2026
QUESTIONS WITH ANSWERS GRADED A+
1. What is the main ion transfer during systole?
A) K⁺ enters, Ca²⁺ seeps out
B) K⁺ seeps out, Ca²⁺ enters
C) Na⁺ enters, K⁺ seeps out
D) Na⁺ and Ca²⁺ both exit the cell
Answer: B
Rationale: During systole (depolarization/contraction), K⁺ exits
the cell down its electrochemical gradient, and Ca²⁺ enters
through L-type channels, initiating myocyte contraction. This
sequence is fundamental to the cardiac action potential and
excitation-contraction coupling.
2. The action potential phase 0 (rapid upstroke) in
non-pacemaker cardiac myocytes is primarily due to:
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A) Ca²⁺ influx
B) K⁺ efflux
C) Na⁺ influx
D) Cl⁻ influx
Answer: C
Rationale: In ventricular and atrial myocytes, the rapid upstroke
(Phase 0) is mediated by fast voltage-gated Na⁺ channels. In
pacemaker cells, Phase 0 is slower and Ca²⁺-mediated.
3. Which of the following best describes the resting membrane
potential of a ventricular myocyte?
A) –90 mV to –80 mV (relative to extracellular fluid)
B) –70 mV to –60 mV
C) 0 mV
D) +30 mV to +40 mV
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Answer: A
Rationale: Ventricular myocytes have a resting membrane
potential of approximately –90 mV, established by the inward
rectifier K⁺ current (IK₁).
4. The normal cardiac impulse originates in the:
A) Atrioventricular (AV) node
B) Bundle of His
C) Sinoatrial (SA) node
D) Purkinje fibers
Answer: C
Rationale: The SA node is the primary natural pacemaker
because of its intrinsic automaticity. It normally fires at 60–100
beats per minute.
5. Which of the following cell layers has the fastest intrinsic
firing rate?
A) AV node
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B) Ventricular myocytes
C) Purkinje fibers
D) SA node
Answer: D
Rationale: The SA node (60–100 bpm) fires faster than the AV
node (40–60 bpm) and Purkinje fibers (15–40 bpm), establishing
it as the dominant pacemaker.
6. The AV node normally provides which of the following
functions?
A) Rapid conduction to the ventricles
B) A delay that allows ventricular filling before contraction
C) Automaticity at a rate of 80–100 bpm
D) Direct activation of the interventricular septum
Answer: B
Rationale: The AV node intrinsically slows conduction, creating a
physiological delay (≈120 ms) that permits the atria to fully
IBHRE ACTUAL EXAM PAPER 2026
QUESTIONS WITH ANSWERS GRADED A+
1. What is the main ion transfer during systole?
A) K⁺ enters, Ca²⁺ seeps out
B) K⁺ seeps out, Ca²⁺ enters
C) Na⁺ enters, K⁺ seeps out
D) Na⁺ and Ca²⁺ both exit the cell
Answer: B
Rationale: During systole (depolarization/contraction), K⁺ exits
the cell down its electrochemical gradient, and Ca²⁺ enters
through L-type channels, initiating myocyte contraction. This
sequence is fundamental to the cardiac action potential and
excitation-contraction coupling.
2. The action potential phase 0 (rapid upstroke) in
non-pacemaker cardiac myocytes is primarily due to:
,Page 2 of 121
A) Ca²⁺ influx
B) K⁺ efflux
C) Na⁺ influx
D) Cl⁻ influx
Answer: C
Rationale: In ventricular and atrial myocytes, the rapid upstroke
(Phase 0) is mediated by fast voltage-gated Na⁺ channels. In
pacemaker cells, Phase 0 is slower and Ca²⁺-mediated.
3. Which of the following best describes the resting membrane
potential of a ventricular myocyte?
A) –90 mV to –80 mV (relative to extracellular fluid)
B) –70 mV to –60 mV
C) 0 mV
D) +30 mV to +40 mV
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Answer: A
Rationale: Ventricular myocytes have a resting membrane
potential of approximately –90 mV, established by the inward
rectifier K⁺ current (IK₁).
4. The normal cardiac impulse originates in the:
A) Atrioventricular (AV) node
B) Bundle of His
C) Sinoatrial (SA) node
D) Purkinje fibers
Answer: C
Rationale: The SA node is the primary natural pacemaker
because of its intrinsic automaticity. It normally fires at 60–100
beats per minute.
5. Which of the following cell layers has the fastest intrinsic
firing rate?
A) AV node
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B) Ventricular myocytes
C) Purkinje fibers
D) SA node
Answer: D
Rationale: The SA node (60–100 bpm) fires faster than the AV
node (40–60 bpm) and Purkinje fibers (15–40 bpm), establishing
it as the dominant pacemaker.
6. The AV node normally provides which of the following
functions?
A) Rapid conduction to the ventricles
B) A delay that allows ventricular filling before contraction
C) Automaticity at a rate of 80–100 bpm
D) Direct activation of the interventricular septum
Answer: B
Rationale: The AV node intrinsically slows conduction, creating a
physiological delay (≈120 ms) that permits the atria to fully
