Cardiac Cycle & ECG — NEET Biology MCQs with Solutions
Free NEET Biology Cardiac Cycle & ECG MCQs with step-by-step solutions (6 questions). Part of Body Fluids and Circulation. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Cardiac Cycle & ECG · easy · theory
The volume of blood pumped out by one ventricle in one heartbeat is the:
A. Cardiac output
B. Residual volume
C. Vital capacity
D. Stroke volume ✓ Correct
Solution: Stroke volume (~70 mL) is the blood ejected per beat by a ventricle.
Q2 — Cardiac Cycle & ECG · easy · theory
In an ECG, the ______ wave represents the depolarisation of the ventricles:
A. P wave
B. QRS complex ✓ Correct
C. U wave
D. T wave
Solution: The QRS complex marks ventricular depolarisation (leading to contraction).
Q3 — Cardiac Cycle & ECG · medium · theory
Cardiac output is calculated as:
A. Stroke volume + heart rate
B. Heart rate ÷ stroke volume
C. Stroke volume − heart rate
D. Stroke volume × heart rate ✓ Correct
Solution: Cardiac output = stroke volume × heart rate (~70 mL × 72/min ≈ 5 L/min).
Q4 — Cardiac Cycle & ECG · medium · theory
The P wave of an ECG corresponds to the ______, and the T wave to the ______:
A. Atrial depolarisation; ventricular repolarisation ✓ Correct
B. Ventricular contraction; atrial relaxation
C. Atrial repolarisation; ventricular depolarisation
D. Ventricular repolarisation; atrial depolarisation
Solution: P = atrial depolarisation; QRS = ventricular depolarisation; T = ventricular repolarisation.
Q5 — Cardiac Cycle & ECG · hard · theory
The first heart sound "lubb" is produced by the closure of the ______ valves at the start of ventricular systole:
A. Semilunar
B. Mitral only
C. Atrioventricular (bicuspid and tricuspid) ✓ Correct
D. Aortic and pulmonary
Solution: "Lubb" (S1) = closure of AV valves (systole begins); "dup" (S2) = closure of semilunar valves (systole ends).
Q6 — Cardiac Cycle & ECG · hard · theory
If a person has a heart rate of 75 beats/min and a stroke volume of 70 mL, the cardiac output is:
A. 5.25 L/min ✓ Correct
B. 52.5 L/min
C. 1.05 L/min
D. 145 mL/min
Solution: CO = 75 × 70 = 5250 mL/min = 5.25 L/min.