MPA 8 Effect of pH on enzyme action

MPA 8 Effect of pH on enzyme action

The enzyme catalase acts on the substrate hydrogen peroxide and produces  water and oxygen. Yeast solution or celery juice can be  used as a source of catalase. 

Mix together chopped celery, water and pH buffer 2 in a test tube and place in a water bath at 30 C. Place hydrogen peroxide in a separate graduated cylinder in the water bath. The water bath keeps the temperature constant and pH buffer is used to maintain a fixed pH.

Leave both solutions in the water bath for 10 minutes to allow time for the enzyme to be affected by the pH. Add the celery extract solution to the hydrogen peroxide. Record the volume of foam produced by oxygen after 10 seconds as a measure of the speed or rate of reaction

Repeat the experiment at different pH‟s using different pH buffers. 

The optimum pH produces the largest volume of foam over the same time. At other pH‟s the enzyme is denatured.

Multiple Choice

Name the substrate for the enzyme catalase.

• Starch

• Protein

• Hydrochloric acid

• Hydrogen peroxide

Multiple Choice

Describe a suitable source for catalase enzyme.

• Celery

• Starch

• Protein

• Hydrogen peroxide

Multiple Choice

State a factor that was kept constant in this investigation

• Light intensity

• Temperature

• Distance to lamp

• pH

Multiple Choice

How is the rate of enzyme action measured in this investigation.

• Volume of foam produced.

• Volume of oxygen foam produced per unit time.

• Concentration of oxygen produced.

• Amount of product produced

Multiple Choice

Name the products of the action of catalase enzyme

• Water

• Oxygen

• Water and carbon dioxide

• Water and oxygen

Multiple Choice

How is the pH varied in this investigation?

• Different pH buffer in each graduated cylinder

• The same pH buffer in each graduated cylinder

• All graduated cylinders are placed in the same water bath.

• Each graduated cylinder is placed in a different water bath at different temperatures.

Multiple Choice

How is the temperature kept constant in this investigation?

• Different pH buffer in each graduated cylinder

• The same pH buffer in each graduated cylinder

• All graduated cylinders are placed in the same water bath.

• Each graduated cylinder is placed in a different water bath at different temperatures.

Multiple Choice

What is meant by the optimum pH for an enzyme.

• The pH it produces.

• The pH it is found in

• The pH that denatures the enzyme

• The pH at which it works fastest