Factors Affecting Enzymes

By Autumn Knoernschild


We studied the effects of different factors on enzyme activity. Enzyme concentration and pH levels can affect an enzyme's ability to catalyze a reaction. We used pressure to measure enzyme activity in an enzyme solution that we created in a test tube.

Research Question

How can we find the effects of different environmental factors on enzyme activity?


Independent Variable: pH level

Dependent Variable: pressure

Constants: temperature of environment, type of enzyme, amount of 3% H2O2


  • LabQuest
  • LabQuest app
  • Vernier Gas Pressure Sensor
  • rubber-stopper assembly
  • 10 mL graduated cylinder
  • 250 mL beaker of water
  • 3% H2O2
  • styrofoam cup to use as a water bath
  • enzyme suspension
  • four 18 x 150 mm test tubes
  • ice
  • pH buffers (pH 4, 7, 10)
  • test tube rack
  • four disposable pipettes
  • Logger Pro
  • goggles


  1. Place three clean test tubes in a rack and label them pH 4, pH 7, and pH 10.
  2. Add 3% H2O2 and each pH buffer to each test tube accordingly
  3. Display the graph on the LabQuest
  4. add 2 drops of the enzyme solution to each test tube

Effects of pH levels on Enzyme Activity

pH Data Hypotheses

Explanatory Hypothesis: Enzyme activity is optimized only after a certain pH

Prediction: Enzyme activity will increase up to a certain point, then begin to decrease

Null Hypothesis: The pH will not affect enzyme activity

Alternative Hypothesis: The pH will affect enzyme actvity

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The enzyme activity in the higher and lower pH levels was not as active as the middle pH level.


Our group's data only goes up to 90 seconds, which was an error on our part. However, our data still proves that the enzyme solution with the mid-level pH showed the most enzymatic activity. Enzymes have an optimum pH level that they perform at and if their environment has extreme pH levels then they will denature.


Enzyme activity will increase up to a certain pH level, but once it reaches its optimum pH the enzyme will denature and enzyme activity will sharply decrease.

Effects of Enzyme Concentration on Enzyme Activity

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Enzyme Concentration Hypotheses

Explanatory Hypothesis: As the enzyme concentration increases the reaction rate increases, which causes enzyme activity to increase

Prediction:The more drops there are, the higher the pressure becomes, so there is higher enzyme activity

Null Hypothesis: The enzyme concentration will not have an effect on enzyme activity

Alternative Hypothesis: The enzyme concentration will have an effect on enzyme activity