Cambridge IGCSE Biology
Cambridge IGCSE Biology 9 Transport in Animals Exam Questions
Free Cambridge IGCSE Biology revision for 9 Transport in Animals: what you need to know, common mistakes and exam-style questions with answers. Covers single and double circulation, the structure of the heart, heart rate, coronary heart disease, arteries, veins and capillaries, and the components of blood.
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About Cambridge IGCSE Biology 9 Transport in Animals
Transport in animals covers the human circulatory system in Cambridge IGCSE Biology. You need to describe circulation as a system of blood vessels with a pump and valves, compare the single circulation of a fish with the double circulation of a mammal, and label the heart, its chambers, valves and major blood vessels. You also need to know how exercise affects heart rate, the risk factors for coronary heart disease, how structure fits function in arteries, veins and capillaries, and the roles of the components of blood. Extended candidates explain the advantages of double circulation and the action of valves. Labelled heart diagrams appear in many papers.
What you need to know
- 9.1 Circulatory systems A fish has a single circulation, with blood passing through the heart once per complete circuit. Mammals have a double circulation: pulmonary circulation to the lungs and systemic circulation to the body. Extended: double circulation keeps a higher blood pressure to the body, so delivery of oxygen and glucose is faster.
- 9.2 Heart structure Right and left atria and ventricles, the septum, atrioventricular and semilunar valves, and coronary arteries. The left ventricle has a thicker muscular wall than the right because it pumps blood at higher pressure all around the body.
- 9.2 Heart activity Heart activity can be monitored using ECG, pulse rate and listening to valve sounds with a stethoscope. Physical activity increases heart rate to supply more oxygen and glucose to muscles and remove more carbon dioxide.
- 9.2 Coronary heart disease Blockage of the coronary arteries reduces oxygen supply to heart muscle. Risk factors include diet high in saturated fat, lack of exercise, stress, smoking, genetic predisposition, age and sex.
- 9.3 Blood vessels Arteries carry blood away from the heart at high pressure and have thick, elastic, muscular walls. Veins carry blood back at low pressure, have thinner walls, a wide lumen and valves. Capillaries have walls one cell thick for exchange of substances with tissues.
- 9.4 Blood Red blood cells carry oxygen using haemoglobin; white blood cells (phagocytes and lymphocytes) defend against pathogens; platelets help clotting; plasma transports nutrients, hormones, carbon dioxide, urea and blood cells. Extended: clotting converts fibrinogen to fibrin to stop blood loss and prevent pathogen entry.
Common mistakes in 9 Transport in Animals
- Saying the left ventricle wall is thicker because it pumps more blood. Both ventricles pump the same volume; the left pumps at higher pressure around the whole body.
- Confusing the sides on a heart diagram. The diagram shows the heart as if you are facing the person, so the left side is on the right of the page.
- Saying arteries carry oxygenated blood. Arteries carry blood away from the heart; the pulmonary artery carries deoxygenated blood.
- Saying capillaries have thin walls 'so blood can get out'. The walls are one cell thick for a short diffusion distance; blood cells stay inside.
- Saying platelets clot the blood alone. Platelets start clotting, which involves fibrinogen being converted to insoluble fibrin.
Try three 9 Transport in Animals exam-style questions
1. Name the blood vessel that carries blood from the heart to the lungs. (1 mark)
Show the mark scheme answer
Pulmonary artery.
2. Explain why the wall of the left ventricle is thicker than the wall of the right ventricle. (2 marks)
Show the mark scheme answer
The left ventricle pumps blood all around the body (systemic circulation); it needs to produce a higher pressure (than the right, which pumps only to the lungs).
3. Describe how the structure of a vein is related to its function. (3 marks)
Show the mark scheme answer
Wide lumen reduces resistance to blood flow at low pressure; valves prevent backflow of blood; thin walls as blood is at low pressure (and nearby muscles squeeze veins to help return blood).
9 Transport in Animals FAQs
What does Cambridge IGCSE Biology 9 Transport in Animals cover?
It covers single and double circulation, heart structure and activity, coronary heart disease, the structure of arteries, veins and capillaries, and the components of blood.
Which paper is 9 Transport in Animals examined in?
It is examined in the theory and multiple choice papers: Papers 1 and 3 for Core candidates, or Papers 2 and 4 for Extended candidates. Practical skills linked to it can also appear in Paper 5 (Practical Test) or Paper 6 (Alternative to Practical).
How do I learn the route of blood through the heart?
Trace it from the vena cava into the right atrium, through the valve to the right ventricle, out of the pulmonary artery to the lungs, back via the pulmonary vein to the left atrium, then the left ventricle and out through the aorta. Practise labelling unlabelled diagrams.
