Ventilation, smoking and exerciseIB MYP Sciences: Mind map

Exam questions on Ventilation, smoking and exercise

1. A physiotherapist in Lagos is teaching a patient how breathing works. She explains that air moves in and out of the lungs because the pressure inside the chest changes whenever the volume of the chest changes.
   Explain how air is forced out of the lungs during normal exhalation.2 marks
2. A student in Auckland uses gas sensors to compare the air she breathes in with the air she breathes out. Inhaled air contains about 21% oxygen and 0.04% carbon dioxide. Exhaled air contains about 16% oxygen and about 4% carbon dioxide, and it is saturated with water vapour.
   Suggest why exhaled air contains more water vapour than inhaled air.2 marks
3. A class in Singapore investigates how exercise affects breathing rate. Each student sits quietly and counts their breaths for one minute. They then step up and down on a bench for two minutes and count their breaths during the next minute. The class mean was 15 breaths per minute at rest and 28 breaths per minute after exercise. Each student counted their own breaths.
   State a hypothesis for this investigation, with a scientific reason, and identify the dependent variable.3 marks