Cardiac output, ventilation and exerciseEdexcel International A Level Biology: Mind map

Exam questions on Cardiac output, ventilation and exercise

1. During a fitness test, a student's heart rate and stroke volume were measured at rest and during vigorous exercise. At rest: heart rate 70 beats per minute and stroke volume 75 cm³. During vigorous exercise: heart rate 150 beats per minute and stroke volume 110 cm³.
   Explain how the change in cardiac output allows the muscles to respire aerobically at a high rate during exercise.2 marks
2. A researcher investigates how the body responds when blood carbon dioxide concentration rises during exercise. As the muscles respire faster they release more carbon dioxide into the blood, which lowers the blood pH. Chemoreceptors in the walls of the carotid arteries and the aorta are sensitive to this change.
   Explain how a rise in blood carbon dioxide concentration leads to an increase in heart rate.2 marks
3. A student breathes in and out of a spirometer containing soda lime, first at rest and then during vigorous exercise on a cycle ergometer. The results were: at rest, tidal volume 0.50 dm³, breathing rate 12 breaths per minute and oxygen consumption 0.30 dm³ per minute; during exercise, tidal volume 2.0 dm³, breathing rate 30 breaths per minute and oxygen consumption 2.4 dm³ per minute.
   Calculate the respiratory minute ventilation at rest and during exercise, and the percentage increase on exercising.3 marks