Describe and carry out investigations using simple respirometers to determine the effect of temperature on the rate of respiration

Sourav PanOctober 31, 2024

Answered

Investigation: Effect of Temperature on the Rate of Respiration using Simple Respirometers

Objective:
To design and conduct an experiment using simple respirometers to investigate how temperature affects the rate of respiration in a living organism (e.g., insects, germinating seeds).

Theory:

• Respiration: The process by which organisms generate energy from glucose, consuming O2 and producing CO2.
• Respirometer: A device measuring the volume of gases exchanged during respiration.
• Temperature’s Effect on Respiration: Enzyme activity and metabolic rate are influenced by temperature, impacting the rate of respiration.

Materials:

• Simple respirometers (e.g., syringe or pipette-based)
• Thermometer
• Water baths or temperature-controlled chambers (at least three different temperatures, e.g., 10°C, room temperature, 30°C or 50°C)
• Living organisms (e.g., insects like mealworms or crickets, or germinating pea seeds)
• Control setup (e.g., without organism or with non-germinating seeds and beads for volume equivalence)

Procedure:

1. Setup Respirometers:
   • Place the organism in the respirometer.
   • Ensure the respirometer is airtight and the gas exchange is measurable (e.g., via water displacement in a pipette).
2. Temperature Control:
   • Place each respirometer in a different temperature-controlled water bath.
   • Monitor temperatures with thermometers.
3. Measure Gas Exchange:
   • Record initial and final gas volumes (or water levels) over a set period (e.g., 10-30 minutes).
   • Repeat measurements for accuracy.
4. Control Setup:
   • Run a control respirometer without an organism or with a non-germinating seed setup to account for any temperature-induced volume changes not related to respiration.

Data Analysis:

1. Calculate Rate of Respiration:
   • ΔVolume (mL) / Time (min) = Rate of Respiration (mL/min)
2. Correct for Temperature-Induced Volume Changes:
   • Apply the ideal gas law (PV = nRT) to adjust volumes for temperature differences, if necessary.
3. Graphical Representation:
   • Plot Rate of Respiration (mL/min) against Temperature (°C).
   • Include error bars, if applicable.

Expected Results:

• Optimum Temperature: The rate of respiration will likely peak at a temperature around 20-30°C for many organisms, reflecting the optimal temperature for enzyme activity.
• Temperature Extremes: Rates of respiration will decrease at lower (e.g., 10°C) and higher (e.g., 50°C) temperatures, due to reduced enzyme activity and potential denaturation, respectively.

Example Data and Graph:

Graph: Rate of Respiration (mL/min) vs. Temperature (°C)

• The graph will show a peak at around 30°C, with lower rates at 10°C and 50°C, illustrating the effect of temperature on the rate of respiration.

Safety and Tips:

• Handle living organisms gently and humanely.
• Ensure accurate temperature control and measurement.
• Minimize experimental variability by maintaining consistent respirometer setups and measurement times.