HSA 2007 Biology Item 24

Use the information and the graph below to answer the following question.

Catalase is an enzyme found in plant and animal cells. Hydrogen peroxide is a harmful substance found in cells. Catalase causes hydrogen peroxide to break down into water and oxygen.

A student conducted an experiment to determine whether plant and animal cells have the same amount of catalase. She used liver and potato tissues in the experiment. The student followed the procedures below.

1. Label two identical test tubes, 1 and 2.
2. Pour 10 milliliters of hydrogen peroxide solution (1% concentration) into each test tube.
3. Add a small piece of liver tissue to Test Tube 1.
4. Add a small piece of potato tissue to Test Tube 2.
5. Collect the oxygen released from each test tube for 25 seconds.
6. Measure and record the volume of oxygen for each test tube.

The graph below shows the results from the experiment.

The student conducted a second experiment. She boiled the liver tissue completely and added it to the hydrogen peroxide solution. She observed that little to no oxygen was released in the second experiment.

Which of these statements best supports the student’s observations?

1. Exposing catalase to high temperatures makes it inactive.
2. Exposing catalase to high temperatures changes it into a different enzyme.
3. Boiling liver breaks down hydrogen peroxide faster.
4. Boiling removes oxygen from the liver.