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The heart and circulation — WBI11 IAL Biology practice questions · Study-IAL

Subjects
Biology
WBI11
1.2

The heart and circulation

WBI11Topic 1.23 questions

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Mass transport, blood vessels, the cardiac cycle, atherosclerosis and blood clotting.

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Questions

Multiple choice: 1
Short answer: 2
Total: 3

Previous topic1.1Water, carbohydrates and lipids Next topic 1.3Cardiovascular disease, diet and risk

Sample questions

Original practice questions written in the style of the exam.

Question 14 marks
Explain how the structure of an artery is related to its function.
Mark scheme
- Thick layer of elastic fibres, so the wall can stretch when blood is pumped in at high pressure (1)
- Elastic recoil smooths the flow / maintains pressure between heartbeats (1)
- Thick layer of smooth muscle, which contracts to alter the diameter of the lumen / control blood flow (1)
- Collagen in the outer layer gives strength so the wall does not burst under high pressure (1)
Question 24 marks
Describe the sequence of events that leads to the formation of a blood clot after a blood vessel is damaged.
Mark scheme
- Platelets / damaged tissue release thromboplastin (1)
- Thromboplastin catalyses the conversion of prothrombin into thrombin (in the presence of calcium ions) (1)
- Thrombin catalyses the conversion of soluble fibrinogen into insoluble fibrin (1)
- Fibrin forms a mesh of fibres that traps platelets and red blood cells (1)