Factors Affecting Enzymes Lab

by Sarah McDonald

Research Question

How do different variables affect the rate of enzymatic activity?


Independent Variable: The temperature of the water that the test tube was set in

Dependent Variable: The pressure resulting from the enzymatic activity

Constants: The concentration, or number of drops, of the enzyme solution, the concentration of hydrogen peroxide and water in each test tube, and the duration time of the reactions


Explanatory hypothesis: We hypothesize that on average, an increased temperature will increase the enzymatic activity.

Prediction: If the temperature is increased, then the rate of the enzyme activity will increase.

Null hypothesis: The temperature will have no effect on the rate of the enzyme activity.

Alternative hypothesis: The temperature will have an effect on the enzymatic activity.


  • LabQuest
  • LabQuest app
  • Rubber-stopper assembly
  • Vernier Gas Pressure Sensor
  • 10 mL graduated cylinder
  • 250 mL beaker of water
  • 3% hydrogen peroxide
  • Styrofoam cup
  • Enzyme suspension
  • four 18 x 150 mm test tubes
  • ice
  • thermometer
  • four disposable pipettes
  • Logger Pro


The same amount of hydrogen peroxide and water was added into each of the four test tubes (3 mL of each substance) and each of the test tubes were placed into a styrofoam cup with the differing temperatures of water (0-5 degrees C, 20-25 degrees C, 30-35 degrees C, and 50-55 degrees C). 2 drops of yeast, the enzyme, were placed into each test tube. 5 minutes were waited out for the mixture to reach the temperature range. We then used the Lab Quest to record the pressure inside the test tube because oxygen was released as a result of the catalase breaking down the hydrogen peroxide into water and oxygen. The pressure was measured for 180 seconds for each of the 4 different temperatures experimented. Goggles and closed-toed shoes were worn throughout the experiment. An example of the set up in depicted in the diagram below.
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Data and Results

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According to the data obtained and that is depicted in this graph, we can see the relationship between the temperature and the enzyme activity. It is clear that the increase in temperature results in increased enzymatic activity.
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According to the data obtained and that is depicted in the graph, we can see that there is a relationship between the rate of reaction and the varying temperatures. It can be suggested that the temperature 30-35 degrees Celsius is not an ideal temperature for the enzymes to work due to the decrease in the rate of reaction.

Conclusion and Discussion

In this experiment testing the effect of varying factors (temperature) on enzymatic activity, it can be concluded that the alternative hypothesis can be accepted and the null hypothesis rejected. The differing temperatures did in fact have an effect on the enzymatic activity, increasing or decreasing the rate, and further suggesting that there could be an optimum temperature for the enzyme catalase to work at. The enzyme catalase appeared to work more efficiently when working at a higher temperature of 50-55 degrees Celsius and a lower efficiency at 0-5 degrees Celsius, according to the data. There may have been some error in the collection of the data such as the time taken to put the stopper onto the test tube (oxygen could have already been released from the reaction), and also the keeping the temperature of the water constant during the trials. These could have been fixed by injecting the enzyme into the test tube so as to not lose the oxygen that is immediately released from the reaction, and having an electrical device that maintains the temperature of the water during the trials.