Gas exchange and breathingIB MYP Sciences: Mind map

Exam questions on Gas exchange and breathing

1. A museum in Cape Town has an interactive display that follows the path of air as a visitor breathes in. The display labels the structures that air passes through and the muscles and bones that move when we breathe.
   Describe two functions of the ribcage in the respiratory system.2 marks
2. In the lungs, oxygen moves from the air into the blood and carbon dioxide moves from the blood into the air. This happens in the alveoli, tiny air sacs that are each surrounded by a network of capillaries.
   Explain why oxygen diffuses from the alveoli into the blood.2 marks
3. A student in Mumbai wants to find out how surface area affects how quickly substances diffuse, as a model of the alveoli. She cuts three identical 2 cm cubes of agar jelly containing alkali and a pink indicator. She leaves one cube whole, cuts one into 8 equal pieces and cuts one into 27 equal pieces. She places each set in the same volume of dilute hydrochloric acid at 20 °C and times how long it takes for all the pink colour to disappear as the acid diffuses in. The whole cube took 420 s, the 8 pieces took 200 s and the 27 pieces took 135 s.
   Identify the independent variable, the dependent variable and one control variable in the student's investigation.3 marks