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← Theoretical 1

Q26 — Cardiac Cycle — Valve Timing and Pressure Changes

Theoretical 1 Real exam question — full text reproduced under IBO's CC BY-NC-SA 4.0 license
Cardiovascular Physiology

The diagram shows the change in pressure over time in the left half of the heart and in the aorta. The duration of this cardiac cycle is 0.6 seconds. At points 1, 2, 3, and 4, the atrioventricular valves and semilunar valves either open or close.

Graph of pressure vs. time for the left ventricle, aorta, and left atrium across one cardiac cycle. Pressure vs. time during the cardiac cycle — pressure change in the left ventricle, the aorta, and the left atrium.

Using the information and figure, determine whether the following statements are true or false. During the cardiac cycle:

A. The atrioventricular and semilunar valves close simultaneously for 0.07 seconds.
B. The atrioventricular valves are closed for 0.28 seconds.
C. The semilunar valves are closed for 0.07 seconds.
D. The semilunar valves are open for 0.28 seconds.
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Question reproduced from IBO 2022, Theoretical Paper 1, licensed under CC BY-NC-SA 4.0 — attributed to the International Biology Olympiad. Open the full exam PDF · Community solutions (unofficial)