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Date November 2009 Marks available 2 Reference code 09N.3.SL.TZ0.5
Level Standard level Paper Paper 3 Time zone TZ0
Command term Outline Question number 5 Adapted from N/A

Question

Draw a labelled diagram to show the structure of a skeletal muscle sarcomere.

[3]
a.

Outline the role of myoglobin in muscle fibres.

[2]
b.

Markscheme

Award [1] for each structure clearly drawn and correctly labelled.

light and dark bands;

Z line;

(thin) actin filaments shown with no gap between these and Z line;

(thick) myosin filaments shown with heads;

a.

binds oxygen when level is high;

releases oxygen when level is low;

acts as an oxygen store;

allows muscles to continue with aerobic respiration for longer;

b.

Examiners report

Some very poor diagrams were seen. The structure of a skeletal muscle was drawn by many of the candidates, without showing the sarcomere.

a.

Many candidates knew that myoglobin is used as an oxygen store.

b.

Syllabus sections

Option D: Human physiology » Option D: Human physiology (Additional higher level topics) » D.6 Transport of respiratory gases
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