Gas exchange and breathingIB MYP Biology: Subtopic test

1. 1
   A swimmer in Sydney takes a deep breath before a race. Her chest expands and air flows down her airways into her lungs.

   (a)

   Which row describes what happens during inhalation?

   [1 mark]

   • AThe diaphragm relaxes and rises; the ribs move down and in
   • BThe diaphragm contracts and flattens; the ribs move down and in
   • CThe diaphragm contracts and flattens; the intercostal muscles contract and the ribs move up and out
   • DThe diaphragm relaxes and flattens; the ribs move up and out

   (b)

   In which order does air pass through the structures of the gas exchange system on its way to the alveoli?

   [1 mark]

   • ABronchi, trachea, bronchioles
   • BTrachea, bronchioles, bronchi
   • CBronchioles, bronchi, trachea
   • DTrachea, bronchi, bronchioles

   (c)

   Explain why air flows into the lungs when the diaphragm contracts.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A student in Dublin compares the carbon dioxide in air from the atmosphere with the carbon dioxide in air she breathes out. In tube A she breathes out through a straw into limewater for 1 minute. In tube B she uses a pump to bubble the same volume of air from the room through the same volume of limewater. Limewater turns cloudy when carbon dioxide is present. The limewater in tube A turns cloudy after 20 seconds. The limewater in tube B is still clear after 4 minutes.

   (a)

   Which conclusion is best supported by the results?

   [1 mark]

   • AExhaled air contains more carbon dioxide than air from the atmosphere
   • BExhaled air contains more oxygen than air from the atmosphere
   • CAir from the atmosphere contains no carbon dioxide
   • DLimewater turns cloudy with oxygen

   (b)

   Which variable is most important to keep the same in tubes A and B?

   [1 mark]

   • AThe age of the student
   • BThe volume of limewater
   • CThe length of the straw
   • DThe colour of the boiling tube

   (c)

   Limewater only shows whether carbon dioxide is present. Suggest one improvement that would allow the student to compare the amounts of carbon dioxide more accurately.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A biology student in Toronto is comparing how a human lung and a leaf are adapted for gas exchange. Both have structures that allow oxygen and carbon dioxide to diffuse in and out of the organism.

   (a)

   Describe how the guard cells control the movement of gases in and out of a leaf.

   [3 marks]

   (b)

   Describe how the alveoli are adapted for efficient gas exchange.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   The government of a country in South-East Asia is considering a law to ban smoking in all indoor public places such as restaurants, offices and shopping centres. The ban would also apply to workers in these places. Many smokers and some business owners say the law goes too far.

   (a)

   Explain the harmful effects of tobacco smoke on a smoker's gas exchange system and blood.

   [6 marks]

   (b)

   Discuss and evaluate the proposed ban on smoking in indoor public places.

   [6 marks]

   Total for question 4: 12 marks

End of questions