Enzyme Activity

Biology Experiment - Enzyme Activity
Part A – pH
Aim: To investigate the effects of change in pH on enzyme activity.
Hypothesis: Hydrogen Peroxidase works best at a neutral pH.
Equipment List:
3 test tubes
Hydrochloric Acid
Sodium Hydroxide
Water
Test tube rack
Eyedropper
3 pea-sized pieces of sheep liver
30cm ruler
Risk Assessment:
Risk
Injury
Evasion of risk
Knife
Laceration of skin when cutting liver
Take care with knife, have supervision
Chemicals
Skin can become irritated or eroded from chemical contact
Wear goggles, and handle chemicals with care.

Method:
Add 20 drops of Hydrogen Peroxide to 3 test tubes.
Add 20 drops of 1M HCl to one test tube; add 20 drops of NaOH to another test tube; add 20 drops of H2O to the last test tube.
Add an equally sized (Pea-size) piece of sheep liver to each test tube.
Measure the height of the bubbles produced using a ruler.

Results:
ph
Height of bubbles
HCl
3 mm
H2O
8 mm
NaOH
5 mm

















Conclusion: The enzyme was most reactive at a neutral pH, as shown by the height of bubbles in the water test tube.
Discussion:
This experiment did test the hypothesis. The reason the experiment created these results is because the enzyme works best in a neutral solution, as our body is filled with liquids of a neutral pH level. Validity: The experiment Is valid because it had independent variables (pH level), dependent (Height of bubbles), and controlled variables (Amount of liquids, size of liver piece, etc.) Accuracy: The experiment is not accurate as there was no definitively calibrated equipment used, and parallax error was a major possibility when measuring the height of the bubbles. Reliability: The results are reliable because were consistent across the class groups. Improvements: Use calibrated equipment.

Part B – Temperature
Aim: To test the effects of temperature on the activity of enzymes.
Hypothesis: The enzymes will work best at room temperature.


Equipment List:
4 test tubes
Water baths (80 C°, 35 C°)
Room temperature water
Beaker
Ice water baths
4 pieces of liver (Pea sized)
30 cm ruler
Hydrogen Peroxide
Risk Assessment:
Risk
Injury
Evasion
Knife
Laceration of hand when cutting liver
Handle knife with care, adult supervision
Boiling water
Can harm if comes in contact with skin
Don't touch the water directly, handle with care

Method:
Add 20 drops of hydrogen peroxide to each of the 4 test tubes.
Warm one test tube in a water bath of 80 C°
Warm the second test tube in a water bath of 35 C°
Place the third test tube in a beaker of room temperature water.
Place the fourth test tube in the ice water bath.
Cut the liver into 4 equally small, pea-sized amounts.
Place one piece of liver in each test tube.
Measure the bubble height with a ruler.
Results:
Temperature (C°)
Height of bubbles (mm)
5 C°
13 mm
23 C°
100 mm
35 C°
75 mm
80 C°
12 mm



Conclusion: The enzyme is most reactive at temperatures close to room temperature and body temperature.
Discussion: The experiment did test the effect of a varying temperature, thus testing the hypothesis. The reason the experiment gave these results is that enzymes are used to working at body/room temperatures, as that's what the temperature is like inside the body of a human. Validity: The experiment is accurate, as it had independent variables (Temperature), Dependent variables (Height of bubbles), and controlled variables (pH, concentration of enzyme concentration). Accuracy: The experiment was not accurate as the temperature of the contents of each test tube was not definitely the temperature it should have been, and again, parallax error was a possibility. Reliability: The experiment is reliable as the results were the same across the class groups. Improvements: Have the contents of each test tube heated to the temperature wanted definitively.

Part C – Substrate Concentration
Aim: To test the effects of substrate concentration on enzyme activity.
Hypothesis: The height of the bubbles will increase as the concentration of substrate increases.
Equipment List:
3 test tubes
Hydrogen Peroxide
Test tube rack
Eyedropper
3 pea-sized pieces of sheep liver
30cm ruler

Risk Assessment:
Risk
Injury
Evasion of risk
Knife
Laceration of skin when cutting liver
Take care with knife, have supervision
Chemicals
Skin can become irritated or eroded from chemical contact
Wear goggles, and handle chemicals with care.

Method:
Collect 3 test tubes
Add 20 drops of 1.5% H2O2 to one test tube, 20 drops of 3% H2O2 to the second test tube and 20 drops of 6% H2O2 to the third.
Cut the liver into 3 equal pea sized pieces
Place each liver piece in each of the three test tubes and measure the height of the bubbles with a ruler.
Results:
Substrate Concentration (%)
Height of bubbles (mm)
1.5
7
3
17
6
27


Conclusion: The more substrate there is, the more enzyme activity there is.
Discussion: The experiment did test the hypothesis. The experiment presented these results because the more substrate there is for the enzyme to react upon, the more the presence of the bi-product of bubbles. Validity: The experiment is valid because it had an independent variable (substrate concentration), Dependent variable (Height of bubbles) and controlled variables (pH, temperature). Accuracy: The experiment is not accurate because the results are made up, as the liver had gone rotten before it could be used a second day. Reliability: Not reliable at all, as the results are completely randomised.
Blake Thomson










pH Affecting Enzyme Activity