Biology Practical for Catalyse

Topics: PH, Enzyme, Chemical reaction Pages: 21 (1758 words) Published: January 29, 2014
Maintaining a Balance – Enzyme Activity
1.P.1 Identify data sources, plan, choose equipment and perform a FHI to test the effect; increased temperature, change in pH and change in substrate concentrations on the activity on the activity of a named enzyme Introduction: Enzymes are catalysts which aid in process of chemical reactions within living organisms. Enzymes increase the rate of biochemical reactions without causing any permanent chemical change to itself. A substrate is the chemical substance on which the enzymes acts upon. Enzymes require different conditions in order to maintain maximum efficiency. Without these conditions being as the enzyme requires, it may affect the activity of an enzyme to the point where is no longer serves its vital function. Three factors are temperature, pH and substrate concentration. Catalase is an enzyme that is found in most living cells in the blood that catalyses the decomposition of hydrogen peroxide into water and oxygen.



Aim: to test the effect of temperature increase, change in pH and change in substrate concentrations on the enzyme; catalase, in the form of potato Hypothesis: the optimum temperature for catalase is room temperature, so the enzyme will react best with the beaker of water around 27-30°c. The optimum pH for catalase is around neutral (7) so the catalase’s rate of activity will be best in the water compared to the acid and alkaline. The test tube with the most hydrogen peroxide will react the most and produce the greatest height of bubbles.

Risk assessment:
1. Wear safety precautions, such as a goggles when handling the chemicals, especially hydrogen peroxide and hydrochloric acid and sodium hydroxide because these chemicals are corrosive and can cause skin damage 2. Handle equipment such as the Bunsen burner and glass apparatus carefully to prevent injury

Materials:
3 x potato

- 30ml sodium hydroxide (NaOH) 1M

- 1 x potato borer

- 10 x litmus paper and pH colour chart

- 8 x 250ml beakers

- 3 x thermometers

- 20 x medium test tubes

- 12 x ice cubes

- 2 x medium test tube racks

- 1 x knife

- 1 x bunsen burner

- 3 x rulers

- 2 x tripods

- 100ml distilled water

- 1 x gauze mat

- 2 x droppers

- 2 x measuring cylinders
- 1 x pack of matches
- 2 x spoons
- 100ml hydrogen peroxide (H₂O₂) 1M
- 30ml 6% hydrochloric acid (HCl) 1M

!
Method:

PART 1 – Increased temperature
1. Collect all necessary equipment and set up apparatus.
2. Use the borer to obtain pieces of potato which can be cut with a knife into equal 1cm piece
3. Pour 10mL of hydrogen peroxide into test tube 1 and place it in a beaker 1 filled with 150ml room temperature water with a thermometer.
4. Place ice cubes and water in the beaker 1 and measure with thermometer until it reaches 10°C.
5. Pour 10mL of hydrogen peroxide into test tube 2 and place it in beaker 2

with 150mL of water. Place beaker on a gauze mat on a tripod. 6. Place a Bunsen burner below the tripod. Heat the beaker until it reaches 30-35°c 7. Pour 10mL of hydrogen peroxide into test tube 3 and place into beaker 3 with 150mL of water and a thermometer. Place the beaker on a tripod. 8. Place a Bunsen burner below the tripod. Heat the beaker until it reaches 40-45°c 9. Place 2 1cm potato pieces in each test tube in the beaker and record the height of bubbles and the time taken for the reaction to occur.

10.Repeat the experiment.
Independent Variable: Temperature


Dependant Variable: Enzyme’s Rate of Reaction


Controlled Variable: Class of enzyme (catalase), surface area of enzyme

!
PART 2 – Change in pH
1. Collect all equipment and set up apparatus
2. Use the borer to obtain pieces of potato to be cut with a knife into equal pieces 3. Pour 10mL of water in two test tubes and place them in the rack. Test the pH using litmus paper.
4. Add 10mL of H2O2 in four test tubes and place them in a rack. Test the pH of those using litmus paper.
5. Drop hydrogen...
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