Aim To complete an investigation to find out the effect of temperature on the rate of respiration To use a three way tap

Using the respirometer for aerobic respiration… 1.The NaOH absorbs carbon dioxide, so any carbon dioxide which is released doesn’t add to the volume and pressure of gas in the tube. 2.As oxygen gets used up, the volume and pressure in the tube decrease. This moves the ink towards the test tube. 3.The fluid is returned to its original level by opening the tap. 4.The volume moved is πr 2 d where r is the radius of the tube and d is the distance travelled. This can be done over a particular time period, to work out cm 3 s -1

5. Germinating seeds were used instead of small plants because…. They weren’t photosynthesising so not producing oxygen. 6. The disinfectant… Removed any bacteria which may have been respiring 7. A suitable control would be… Boiled peas, the enzymes would be denatured so they couldn’t respire 8. You would need to control… Number of peas, mass of peas. 9. To make the experiment more reliable… we would need to do more repeats

Setting up anaerobic conditions. See page 14 in booklet – and demo

1.Why was boiled water used to make the yeast suspension? 2.What is the purpose of the oil layer? 3.What other differences are there between this respirometer and the one used for aerobic conditions? 4.In which direction will the fluid in the manometer move? It contains less oxygen than cold water. Prevent oxygen from entering No sodium hydroxide pellets to absorb the carbon dioxide Away from the tube as we are measuring the carbon dioxide produced, which increases the volume a pressure