A student in a different class has designed the investigation shown in Fig. 3.5.2. You have been asked to change this investigation to examine the relationship between temperature and the rate of respiration. The hypothesis is ʻThe higher the temperature, the faster the rate of respiration’.
Plastic tubing Clip
Capillary tube
Seeds
Step 1: Collect the necessary equipment and set up the investigation.
Wire gauze
Soda lime Water bath
1 How will you collect all of the data needed to test your hypothesis? You can use the following incomplete data collection sheet to help you get started, but there are some important factors that are not included. What other data should you collect? Consider the independent, dependent and controlled (fixed) variables needed to make this a fair test.
Fig. 3.5.2
Set-up to investigate the relationship between temperature and the rate of respiration
Independent variable Dependent variable Temperature (°C)
0 10
20 30 40 50
Step 2: You may start your investigation when you are satisfied that your method is appropriate and you have considered all key factors. Record your data. When you have finished collecting your data, consider the following questions:
2 Does this investigation need a control? If yes, what would be a suitable control? 3 Present the data that you have collected and recorded using a suitable chart or graph.
4 Comment on the trend that you have observed. Does this trend support the original hypothesis?
5 Comment on likely sources of error. How could you change the investigation to improve accuracy?
61 Controlled (fixed) variables Rate of respiration (cm) Mass of seeds
