Introduction

The methods section of a biology lab report is crucial as it outlines the procedures and materials used in the experiment. This section not only allows for reproducibility but also provides clarity on how the results were obtained. Below are three diverse examples that illustrate different contexts and methodologies within biology lab reports.

Example 1: Effect of Light Intensity on Photosynthesis

Context

This example is designed for an experiment investigating how varying light intensities affect the rate of photosynthesis in aquatic plants.

The study utilized Elodea plants submerged in water to measure the rate of photosynthesis through oxygen production.

The methods section is structured as follows:

1. Materials:

   • Elodea plants (5 sprigs)
   • Beaker (1 L)
   • Light source (LED lamp)
   • Ruler
   • Stopwatch
   • Thermometer
   • Sodium bicarbonate solution

2. Procedure:

   • Five sprigs of Elodea were placed in a beaker filled with 1 L of water containing 0.5 g of sodium bicarbonate to provide a carbon source.
   • The temperature of the water was maintained at 25°C using a thermometer.
   • An LED lamp was positioned at varying distances (10 cm, 20 cm, 30 cm) from the beaker to create different light intensities.
   • For each distance, the number of oxygen bubbles produced by the plants over a 5-minute period was counted, with three trials conducted for each intensity.

Notes

• Ensure the environment remains consistent throughout the experiment to avoid affecting results.
• It may be beneficial to repeat the experiment at different times of the day to assess variations in photosynthesis.

Example 2: Bacterial Culture and Antibiotic Sensitivity

Context

This example illustrates the methodology for assessing the sensitivity of bacteria to different antibiotics using the agar diffusion method.

The experiment aims to determine the effectiveness of three different antibiotics against E. coli.

1. Materials:

   • Nutrient agar plates (5)
   • E. coli bacterial culture
   • Antibiotics: Penicillin, Tetracycline, Streptomycin
   • Sterile swabs
   • Calipers
   • Incubator (37°C)

2. Procedure:

   • Sterile swabs were used to evenly spread a bacterial culture of E. coli across the surface of each nutrient agar plate.
   • Discs of each antibiotic (6 mm) were placed on the agar surface at equal distances.
   • Plates were incubated at 37°C for 24 hours.
   • After incubation, the zones of inhibition around each disc were measured using calipers to determine the effectiveness of each antibiotic.

Notes

• Ensure aseptic techniques are followed to prevent contamination of cultures.
• Results should be replicated to ensure accuracy and reliability.

Example 3: Investigating the Impact of pH on Enzyme Activity

Context

This example focuses on examining how different pH levels affect the activity of the enzyme catalase, which breaks down hydrogen peroxide.

The methods section is defined as follows:

1. Materials:

   • Fresh potato (for catalase)
   • Hydrogen peroxide solution (3%)
   • pH buffers (pH 4, 7, 10)
   • Test tubes (5)
   • Stopwatch
   • Measuring cylinder

2. Procedure:

   • Potato was blended to extract catalase and then filtered to collect the enzyme solution.
   • Each test tube was filled with 5 mL of pH buffer solution, and 5 mL of hydrogen peroxide was added.
   • A stopwatch was started immediately after adding the enzyme solution (1 mL) to each test tube.
   • The rate of oxygen production was determined by measuring the volume of gas produced in 5 minutes using a gas collection apparatus.

Notes

• Ensure the enzyme is at a consistent concentration for all trials.
• Consider running additional trials at varying temperatures to explore their effects on enzyme activity.