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Question 18M.3.HL.TZ1.a

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Date May 2018 Marks available [Maximum mark: 2] Reference code 18M.3.HL.TZ1.a
Level HL Paper 3 Time zone TZ1
Command term Outline Question number a Adapted from N/A
a.
[Maximum mark: 2]
18M.3.HL.TZ1.a

Outline the role of the sinoatrial node in the contraction of the heart.

[2]

Markscheme

a. initiates action potentials / electrical impulses (at start of cardiac cycle) 

b. acts as pacemaker/ continuous beating without external stimuli 

c. signal spreads over atria / causes contraction of atria (systole) 

d. impulses transmitted to AV (atrioventricular) node / cannot pass directly to ventricles

Syllabus sections