WJEC GCSE Biology 1.4 Circulatory System in Humans Exam Questions

About WJEC GCSE Biology 1.4 Circulatory System in Humans

This topic in Unit 1 covers how blood is pumped around the body to deliver oxygen and glucose and remove waste. You need the components of blood, labelled drawings of a red blood cell and a phagocyte, the structure of the heart and the route of blood through it. You must explain the double circulatory system and how the structures of arteries, veins and capillaries suit their functions. The topic ends with cardiovascular disease: risk factors and treatments such as statins, angioplasty and lifestyle change. It links to gas exchange in 1.2, and examiners often ask for the path of blood through the heart in the correct order.

What you need to know

• Blood Blood has four components: red blood cells (carry oxygen using haemoglobin, no nucleus, biconcave shape), white blood cells such as phagocytes (engulf microbes), platelets (help clotting) and plasma (carries dissolved substances such as glucose, carbon dioxide and urea).
• Heart structure Label the right and left atria and ventricles, tricuspid and bicuspid valves, semi-lunar valves, pulmonary artery, pulmonary vein, aorta and vena cava. Coronary arteries supply the heart muscle itself with oxygenated blood.
• Route through the heart Vena cava, right atrium, tricuspid valve, right ventricle, semi-lunar valve, pulmonary artery to lungs; pulmonary vein, left atrium, bicuspid valve, left ventricle, semi-lunar valve, aorta. Valves prevent backflow.
• Double circulation Blood passes through the heart twice per circuit: the pulmonary circulation to the lungs and the systemic circulation to the body. The left ventricle wall is thicker because it pumps blood all round the body at higher pressure.
• Blood vessels Arteries carry blood away from the heart and have thick muscular, elastic walls for high pressure. Veins return blood to the heart, have thinner walls, a wide lumen and valves. Capillaries have walls one cell thick for exchange with tissues.
• Cardiovascular disease Risk factors include high-fat diet, smoking, lack of exercise and high blood pressure. Treatments include statins (lower blood cholesterol), angioplasty (a balloon or stent widens a narrowed coronary artery) and changes to diet and exercise; each has advantages and disadvantages.

Common mistakes in 1.4 Circulatory System in Humans

• Saying all arteries carry oxygenated blood. The pulmonary artery carries deoxygenated blood to the lungs; arteries are defined as carrying blood away from the heart.
• Mixing up the sides of the heart on a diagram. The heart is drawn as if facing you, so the left side of the heart appears on the right of the page.
• Writing that the left ventricle wall is thicker so it can pump more blood. Both ventricles pump the same volume; the left is thicker to generate higher pressure to reach the whole body.
• Saying capillaries have thin walls so blood flows quickly. Their walls are one cell thick to give a short diffusion distance; blood actually flows slowly through them.

Try three 1.4 Circulatory System in Humans exam-style questions