To investigate how the different concentrations of hydrogen peroxide influences the activity of catalase.

                 Independent variable

        Concentration of hydrogen peroxide solution, 6%, 3%, 1.5%, 0.75%, 0.375%

                  Dependent variable

The rate of breakdown of hydrogen peroxide by catalase is measured in term of time

              Controlled variable

3. Apparatus and Materials

Apparatus

1 retort stand with clamp

1 stopwatch

4 plastic vials

1 goggles

3 60ml syringe

1 10ml measuring cylinder

1 boiling test tube

1 knife

1 pair of scissors

1 pair of forceps

1 ruler up to ± 0.1cm

Materials

100cm3 6% H2O2 solution

100cm3 distilled water

Chicken liver

100cm3 colored liquid

4. Procedure

Please refer to worksheet titled “Investigating factors that influence the activity of catalase”.

Table 1: The procedure for serial dilution to prepare solution containing 6, 3, 1.5, 0.75, and 0.375 hydrogen peroxide respectively.

5. Results

Table 2: showing the time taken for the fluid in the manometer to rise by 5cm in different concentrations of H2O2

Graph

6. Discussion of results

Anomalous results

There are no anomalous results

Results of investigation

As show the values in the graph, there was a decrease trend in the rate of breakdown of hydrogen peroxide after adding different concentration hydrogen peroxide to the chicken liver. The range is from 0.3s to 112s. This indicates that the activity of catalase decreases when the substrate concentration of hydrogen peroxide decreases. Many active sites are not used up at any point in time because the amount of substrate decreases, thus the substrate cannot bind to the active site. When the substrate concentration decreases, this means the “frequency of effective collision between substrate and active sites” will decrease. As a result, the rate of breakdown of hydrogen peroxide by catalase decreases when the concentration of hydrogen peroxide decreases.

The time taken for the fluid in the manometer to rise by 5cm in a concentration of hydrogen peroxide that is longer than the other, this means that the amount of O2 is formed decreases. This also indicates that the activity of catalase decreases because the amount of substrate decreases. Therefore, the rate of reaction also decreases.

       7.         Conclusion

As the concentration of H2O2 solution decreases, the rate of breakdown of hydrogen peroxide by catalase decreases. This agrees with the hypothesis proposed for the investigation

8. Evaluation

       

      9.        References:

        1 + 2:

        3: “IB Diploma Programme Biology (Course Companion)”, Andrew Allott and David Mindorff, Page 75 

 

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