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Date November 2020 Marks available 4 Reference code 20N.2.SL.tz0.4
Level Standard Level Paper Paper 2 Time zone time zone 0
Command term Describe Question number 4 Adapted from N/A

Question

State the function of platelets in response to a skin cut.

[1]
a.

Describe the pathway of the electrical impulse during excitation of the heart muscle.

[4]
b.

Markscheme

platelets help form a clot / scab at the site of the cut;

a.

pacemaker/SA node fires initiate electrical impulse;

impulse travels across the atria walls;

impulse arrives at the AV node <base of the right atrium>;

impulse passes from the AV node down to the bundle of His <through the septum>;

passes down the <left and right> bundle branches <to the apex of the heart>;

travels up through the Purkinje fibres <to stimulate the rest of the ventricles>;

Accept an annotated diagram.
Responses must be in chronological order to be credited, not just a list.

b.

Examiners report

Generally answered correctly.

a.

Generally answered correctly to obtain at least 2 or 3 marks.

b.

Syllabus sections

Topic 2: Exercise physiology » 2.2. Structure and function of the cardiovascular system » 2.2.4. Describe the intrinsic and extrinsic regulation of heart rate and the sequence of excitation of the heart muscle.
Topic 2: Exercise physiology » 2.2. Structure and function of the cardiovascular system
Topic 2: Exercise physiology

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