Gas exchange and breathingIB MYP Biology: Mind map

Exam questions on Gas exchange and breathing

1. A swimmer in Sydney takes a deep breath before a race. Her chest expands and air flows down her airways into her lungs.
   Explain why air flows into the lungs when the diaphragm contracts.2 marks
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.
   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
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.
   Describe how the guard cells control the movement of gases in and out of a leaf.3 marks