Ventilation, smoking and exerciseIB MYP Sciences: Subtopic test

1. 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.

   (a)

   What happens to the diaphragm and the intercostal muscles during inhalation?

   [1 mark]

   • ABoth relax
   • BThe diaphragm relaxes and the intercostal muscles contract
   • CBoth contract
   • DThe diaphragm contracts and the intercostal muscles relax

   (b)

   What happens to the pressure inside the chest during inhalation?

   [1 mark]

   • AIt falls below the pressure of the air outside, so air flows in
   • BIt rises above the pressure of the air outside, so air flows in
   • CIt stays the same, so air is pushed in by the nose
   • DIt falls below the pressure of the air outside, so air flows out

   (c)

   Explain how air is forced out of the lungs during normal exhalation.

   [2 marks]

   Total for question 1: 4 marks

2. 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.

   (a)

   Why does exhaled air contain more carbon dioxide than inhaled air?

   [1 mark]

   • ACarbon dioxide is made by photosynthesis in the alveoli
   • BOxygen is changed into carbon dioxide in the bronchi
   • CThe diaphragm produces carbon dioxide as it contracts
   • DCells make carbon dioxide in respiration and it diffuses from the blood into the alveoli

   (b)

   Why does exhaled air contain less oxygen than inhaled air?

   [1 mark]

   • AOxygen is destroyed in the trachea
   • BSome oxygen diffuses from the alveoli into the blood to be used in respiration
   • COxygen is changed into water vapour in the lungs
   • DOxygen is trapped in the mucus lining the airways

   (c)

   Suggest why exhaled air contains more water vapour than inhaled air.

   [2 marks]

   Total for question 2: 4 marks

3. 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.

   (a)

   State a hypothesis for this investigation, with a scientific reason, and identify the dependent variable.

   [3 marks]

   (b)

   Describe the trend in the class results and evaluate the method, suggesting one improvement.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   Tobacco smoke contains thousands of chemicals, including tar, nicotine and carbon monoxide. A health ministry in a Gulf country is considering a law that would ban smoking in all indoor public places, such as restaurants, shopping malls and offices. Non-smokers in these places breathe in other people's smoke.

   (a)

   Explain how the chemicals in tobacco smoke harm the lungs and the body of a smoker.

   [6 marks]

   (b)

   Discuss the social, economic and ethical implications of banning smoking in all indoor public places, and justify a conclusion.

   [6 marks]

   Total for question 4: 12 marks

End of questions