Apparatus used to investigate whether oxygen is used during aerobic respiration Questions 1. Identify the experiment and the control. Explain your answer. (2) 2. What precaution do you need to take before setting up the experiment? (2) 3. What is the function of the soda lime in the test tube? Explain why this is necessary. • As the beetle respires and uses the gas in the test tube what happens: a) to the volume of the gas in the test tube? (1) b) to the coloured water in the rubber tubing? Why is the test tube kept in water at a constant temperature? (2) What temperature should the water be? Give a reason for your answer. (2) Why is oxygen necessary during aerobic respiration? (2)