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Question 17N.3.SL.TZ0.16b

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Date November 2017 Marks available [Maximum mark: 2] Reference code 17N.3.SL.TZ0.16b
Level SL Paper 3 Time zone TZ0
Command term Explain Question number b Adapted from N/A
b.
[Maximum mark: 2]
17N.3.SL.TZ0.16b

The diagram shows changes in the pressure and volume of the left ventricle during normal heartbeat. The phonocardiogram records heart sounds during the cardiac cycle.

[Source: Wiggers, Carl J. 1923. Modern Aspects of the Circulation in Health and Disease, 2nd ed. Philadelphia: Lea & Febiger, p. 97.]

(b)

Explain the events that cause the sound shown on the phonocardiogram at the start of systole.

[2]

Markscheme

a. when the ventricle contracts blood presses/pressure acts on the AV valve

b. this closes the AV valve «which causes the sound»

The valve must be identified as the AV or atrioventricular valve

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