During a school rowing trial, a sports scientist records the pulse rate of a pupil who becomes breathless sooner than the rest of the team. The scientist us...
Question 1 Report
During a school rowing trial, a sports scientist records the pulse rate of a pupil who becomes breathless sooner than the rest of the team. The scientist uses Fig. 1 to discuss how the heart supplies the body cells with oxygen and glucose in the blood. The arrows show the direction of blood flow. The blood returning from the body has a lower oxygen concentration than blood leaving the lungs.
Fig. 1
(a) What is the name of the chamber labelled X? [1]
(b) What is the function of the structure labelled Y? [2]
(c) Describe the difference in oxygen concentration between the blood in vessel P and the blood in vessel Q. [2]
(d) Explain why a narrowed coronary artery can cause a person to stop exercising. [3]
(e) State two features of red blood cells that help them transport oxygen to body cells. [2]
Answer Details
(a) Chamber X is the left ventricle. [1]
(b) Structure Y is a valve. It prevents backflow of blood and ensures that blood flows in one direction through the heart. [2]
(c) Blood in vessel P has a lower oxygen concentration. Blood in vessel Q has a higher oxygen concentration because it has gained oxygen in the lungs. [2]
(d) A narrowed coronary artery means less blood reaches heart muscle. Less oxygen and glucose are supplied for aerobic respiration, so less energy is released for contraction. The person may become tired or breathless and have to stop exercising. [3]
(e) Red blood cells contain haemoglobin and have a biconcave shape that gives a large surface area. Other acceptable features are no nucleus, giving more space for haemoglobin, and flexibility to pass through narrow capillaries. Any two gain credit. [2]
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