Comprehensive Biology Lab Report: The Effects of
Temperature, pH, and Substrate Concentration on Catalase
Activity in Potato Extract – Complete Example with Data,
Graphs, and Statistical Analysis
Lab Report Example: Biology
Title: The Effect of Temperature on the Activity of
Catalase in Potato Extract
Abstract
This experiment investigated how temperature affects the activity of the enzyme
catalase, which breaks down hydrogen peroxide into water and oxygen. Potato
extract was mixed with hydrogen peroxide at five different temperatures (0°C, 20°C,
37°C, 55°C, and 70°C). The rate of reaction was measured by the height of oxygen
bubble foam produced in 30 seconds. Results showed that catalase activity increased
from 0°C to 37°C, with maximum activity at 37°C (mean foam height = 4.2 cm).
Activity decreased sharply at 55°C and was completely absent at 70°C (mean foam
height = 0 cm). These findings support the hypothesis that enzyme activity increases
with temperature up to an optimal point, after which denaturation occurs.
, 1. Introduction
Enzymes are biological catalysts that speed up chemical reactions without being
consumed. Catalase is an enzyme found in nearly all living organisms, including
plants. Its function is to decompose hydrogen peroxide (H₂O₂), a toxic byproduct of
metabolism, into water and oxygen:
2 H₂O₂ → 2 H₂O + O₂
Enzyme activity is influenced by environmental factors such as temperature, pH, and
substrate concentration. According to the collision theory, increasing temperature
increases molecular motion and collision frequency, thereby increasing reaction rate.
However, beyond a certain temperature (typically 40–50°C for plant enzymes), the
enzyme’s protein structure denatures, losing its active site shape and catalytic ability.
Hypothesis: Catalase activity will increase as temperature rises from 0°C to an
optimal temperature (approximately 37°C), then decrease at higher temperatures
due to denaturation. At 70°C, activity will be completely lost.
Null hypothesis: Temperature has no effect on catalase activity.
2. Materials and Methods
2.1 Materials
Fresh potato (Russet variety)
Blender
Cheesecloth or fine strainer
3% hydrogen peroxide solution (H₂O₂)
Test tubes (5)
Test tube rack
Thermometer
, Water baths set at: 0°C (ice water), 20°C (room temp), 37°C (incubator), 55°C, and
70°C (hot water baths)
Stopwatch
Ruler (mm scale)
Graduated cylinders (10 mL)
Pipettes (5 mL)
Distilled water
2.2 Procedure
1. Potato extract preparation:
A raw potato was peeled, cubed, and blended with 200 mL of distilled water. The
mixture was filtered through cheesecloth to obtain a clear potato extract (crude
catalase solution). The extract was kept on ice.
2. Temperature treatment:
Five test tubes were labeled 0°C, 20°C, 37°C, 55°C, and 70°C. Into each tube, 3 mL of
potato extract was added. The tubes were placed in their respective water baths for 5
minutes to equilibrate.
3. Reaction initiation:
After equilibration, 3 mL of 3% hydrogen peroxide (also pre-warmed to the
corresponding temperature) was added to each tube. The tube was gently swirled
and immediately placed back in the water bath.
4. Measurement:
The height of the oxygen bubble foam column (in cm) was measured after exactly 30
seconds using a ruler. The foam height is proportional to the rate of oxygen
production (catalase activity).
5. Replicates:
The entire procedure was repeated three times for each temperature (n=3). Distilled
water (instead of potato extract) was used as a negative control at 37°C (no foam
expected).
Temperature, pH, and Substrate Concentration on Catalase
Activity in Potato Extract – Complete Example with Data,
Graphs, and Statistical Analysis
Lab Report Example: Biology
Title: The Effect of Temperature on the Activity of
Catalase in Potato Extract
Abstract
This experiment investigated how temperature affects the activity of the enzyme
catalase, which breaks down hydrogen peroxide into water and oxygen. Potato
extract was mixed with hydrogen peroxide at five different temperatures (0°C, 20°C,
37°C, 55°C, and 70°C). The rate of reaction was measured by the height of oxygen
bubble foam produced in 30 seconds. Results showed that catalase activity increased
from 0°C to 37°C, with maximum activity at 37°C (mean foam height = 4.2 cm).
Activity decreased sharply at 55°C and was completely absent at 70°C (mean foam
height = 0 cm). These findings support the hypothesis that enzyme activity increases
with temperature up to an optimal point, after which denaturation occurs.
, 1. Introduction
Enzymes are biological catalysts that speed up chemical reactions without being
consumed. Catalase is an enzyme found in nearly all living organisms, including
plants. Its function is to decompose hydrogen peroxide (H₂O₂), a toxic byproduct of
metabolism, into water and oxygen:
2 H₂O₂ → 2 H₂O + O₂
Enzyme activity is influenced by environmental factors such as temperature, pH, and
substrate concentration. According to the collision theory, increasing temperature
increases molecular motion and collision frequency, thereby increasing reaction rate.
However, beyond a certain temperature (typically 40–50°C for plant enzymes), the
enzyme’s protein structure denatures, losing its active site shape and catalytic ability.
Hypothesis: Catalase activity will increase as temperature rises from 0°C to an
optimal temperature (approximately 37°C), then decrease at higher temperatures
due to denaturation. At 70°C, activity will be completely lost.
Null hypothesis: Temperature has no effect on catalase activity.
2. Materials and Methods
2.1 Materials
Fresh potato (Russet variety)
Blender
Cheesecloth or fine strainer
3% hydrogen peroxide solution (H₂O₂)
Test tubes (5)
Test tube rack
Thermometer
, Water baths set at: 0°C (ice water), 20°C (room temp), 37°C (incubator), 55°C, and
70°C (hot water baths)
Stopwatch
Ruler (mm scale)
Graduated cylinders (10 mL)
Pipettes (5 mL)
Distilled water
2.2 Procedure
1. Potato extract preparation:
A raw potato was peeled, cubed, and blended with 200 mL of distilled water. The
mixture was filtered through cheesecloth to obtain a clear potato extract (crude
catalase solution). The extract was kept on ice.
2. Temperature treatment:
Five test tubes were labeled 0°C, 20°C, 37°C, 55°C, and 70°C. Into each tube, 3 mL of
potato extract was added. The tubes were placed in their respective water baths for 5
minutes to equilibrate.
3. Reaction initiation:
After equilibration, 3 mL of 3% hydrogen peroxide (also pre-warmed to the
corresponding temperature) was added to each tube. The tube was gently swirled
and immediately placed back in the water bath.
4. Measurement:
The height of the oxygen bubble foam column (in cm) was measured after exactly 30
seconds using a ruler. The foam height is proportional to the rate of oxygen
production (catalase activity).
5. Replicates:
The entire procedure was repeated three times for each temperature (n=3). Distilled
water (instead of potato extract) was used as a negative control at 37°C (no foam
expected).
