Lesson 3.1.2b

3.1.2b Heart structure and the cardiac cycle Quiz: OCR Biology, Unit 2

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.1.2b, Heart structure and the cardiac cycle: 20 multiple choice questions for the OCR Biology (H020), Unit 2: Exchange and transport, written with Revision Ninja.

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The 20 questions

  1. Which blood vessels carry blood directly into the atria of the heart?

    • Capillaries
    • Arteries
    • Veins
    • Arterioles

  2. The valves between the atria and ventricles are:

    • Pulmonary valves only
    • Atrioventricular valves
    • Semilunar valves
    • Aortic valves only

  3. Semilunar valves prevent backflow of blood from major arteries into which heart chambers?

    • Venae cavae
    • Ventricles
    • Atria
    • Coronary arteries

  4. What is the primary function of the sino-atrial node in the heart?

    • Delays electrical impulses
    • Pumps oxygenated blood
    • Acts as pacemaker
    • Opens semilunar valves

  5. Why does the atrioventricular node delay the electrical impulse during the cardiac cycle?

    • Heart rate slows
    • Ventricles contract first
    • Atria empty fully
    • Semilunar valves open

  6. What role does Purkyne tissue play in the mammalian cardiac cycle?

    • Initiates atrial impulses
    • Delays cardiac impulses
    • Conducts ventricular impulses
    • Closes heart valves

  7. What does the term myogenic mean when describing cardiac muscle?

    • Lacks electrical activity
    • Initiates own contraction
    • Requires nervous stimulation
    • Contracts only voluntarily

  8. A heart beats 70 times per minute and pumps 70 cm3 per beat. What is the cardiac output?

    • 4.9 dm3 per minute
    • 140 dm3 per minute
    • 490 dm3 per minute
    • 0.049 dm3 per minute

  9. A heart rate of 60 beats per minute gives a cardiac cycle of:

    • 1 second
    • 0.5 seconds
    • 60 seconds
    • 2 seconds

  10. What electrical event in the cardiac cycle is represented by the P wave on an ECG?

    • Atrial repolarisation
    • Ventricular depolarisation
    • Ventricular repolarisation
    • Atrial depolarisation

  11. On an ECG trace, the QRS complex represents:

    • Atrial repolarisation
    • Ventricular repolarisation
    • Ventricular depolarisation
    • Atrial depolarisation

  12. What condition is indicated by tachycardia on an electrocardiogram trace?

    • Extra heartbeat
    • Slow heart rate
    • Fast heart rate
    • Chaotic heart rhythm

  13. What condition is indicated by bradycardia on an electrocardiogram trace?

    • Chaotic heart rhythm
    • Extra heartbeat
    • Slow heart rate
    • Fast heart rate

  14. What feature characterises cardiac fibrillation on an ECG trace?

    • Chaotic electrical activity
    • Slow heart rate
    • Normal wave pattern
    • Fast heart rate

  15. What describes an ectopic heartbeat during a cardiac cycle?

    • Constant fast rhythm
    • Unusually slow rhythm
    • Early extra heartbeat
    • Chaotic muscle contraction

  16. During which phase of the cardiac cycle does ventricular pressure rise sharply?

    • Cardiac diastole
    • Ventricular systole
    • Ventricular diastole
    • Atrial systole

  17. Stroke volume is 80 cm3 and heart rate is 75 beats per minute. What is the cardiac output?

    • 6000 cm3 per minute
    • 75 cm3 per minute
    • 155 cm3 per minute
    • 80 cm3 per minute

  18. What is the main function of the atrioventricular node during the cardiac cycle?

    • Pumping ventricular blood
    • Preventing backflow
    • Delaying electrical impulses
    • Initiating heartbeats

  19. Why is the muscular wall of the left ventricle thicker than the right ventricle wall?

    • Pumps larger volume
    • Slows blood flow
    • Prevents backflow
    • Generates higher pressure

  20. A heart pumps 5 dm3 per minute at 100 beats per minute. What is the stroke volume?

    • 500 cm3
    • 5 cm3
    • 20 cm3
    • 50 cm3

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