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IGCSE Biology · 0610

IGCSE Biology: Transport in Animals and the Heart Questions

The heart and blood vessels are guaranteed marks if you know the structure to function links. These questions cover why the left ventricle wall is thicker, the job of the valves and how arteries and veins differ.

What you need to know

  • The heart has four chambers: two atria receive blood, two ventricles pump blood out.
  • The left ventricle has a thicker muscular wall because it pumps blood to the whole body at high pressure.
  • Valves prevent the backflow of blood and keep it moving in one direction.
  • Arteries carry blood away from the heart at high pressure, veins return blood at low pressure and have valves.
A B C D A,B atria C,D ventricles
Simplified heart: A and B are the atria, C and D are the ventricles. D, the left ventricle, has the thicker wall.

Practice questions with answers

Question 12 marks

Explain why the wall of the left ventricle is thicker than the wall of the right ventricle.

The left ventricle pumps blood to the whole body, which is a long distance and needs high pressure, so it has a thick muscular wall. The right ventricle only pumps blood a short distance to the lungs at lower pressure, so its wall is thinner.

Mark schemeLeft ventricle pumps to the whole body, further, at higher pressure (1). Right ventricle pumps only to the lungs, shorter, lower pressure (1).

Common mistakeSaying the left side carries more blood. Both sides pump equal volumes; the difference is pressure and distance.

Exam tipCompare both ventricles in your answer. A comparison question wants both sides addressed.

Question 22 marks

State the function of the valves in the heart.

The valves prevent the backflow of blood. They ensure that blood flows in one direction only through the heart.

Mark schemePrevent backflow (1). Ensure one-way flow (1).

Common mistakeSaying valves pump blood. Valves do not pump; they control the direction of flow.

Exam tipThe exact phrase prevent backflow reliably scores. Use it.

Question 33 marks

Compare the structure of an artery and a vein.

An artery has a thick muscular and elastic wall with a narrow lumen and carries blood away from the heart at high pressure. A vein has a thinner wall, a wider lumen and valves, and carries blood back to the heart at low pressure.

Mark schemeArtery thick wall, narrow lumen (1). Vein thinner wall, wider lumen, valves (1). Correct direction or pressure for each (1).

Common mistakeConfusing which vessel has valves. Veins have valves; arteries do not.

Exam tipStructure your answer as artery then vein so the examiner can pair each point.

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Frequently asked questions

Why is the left ventricle wall thicker?

It pumps blood to the whole body at high pressure over a long distance, so it needs more cardiac muscle than the right ventricle, which only pumps to the lungs.

What is double circulation?

Blood passes through the heart twice for each full circuit of the body: once to the lungs, once to the rest of the body. This keeps oxygenated and deoxygenated blood separate.

Which blood vessels have valves?

Veins have valves to prevent backflow because blood in them is at low pressure. Arteries do not need valves because blood in them is at high pressure.

What is the job of capillaries?

Capillaries have very thin walls, one cell thick, that allow oxygen, glucose and other substances to diffuse quickly between blood and cells.

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