AS and A Level Biology 20 Views 1 Answers
Describe and carry out investigations using simple respirometers to determine the effect of temperature on the rate of respiration
Describe and carry out investigations using simple respirometers to determine the effect of temperature on the rate of respiration
Answered step-by-step
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:
- 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).
- Temperature Control:
- Place each respirometer in a different temperature-controlled water bath.
- Monitor temperatures with thermometers.
- 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.
- 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:
- Calculate Rate of Respiration:
- ΔVolume (mL) / Time (min) = Rate of Respiration (mL/min)
- Correct for Temperature-Induced Volume Changes:
- Apply the ideal gas law (PV = nRT) to adjust volumes for temperature differences, if necessary.
- 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:
Temperature (°C) | ΔVolume (mL) | Time (min) | Rate of Respiration (mL/min) |
---|---|---|---|
10 | 2 | 30 | 0.067 |
Room (22) | 8 | 30 | 0.267 |
30 | 12 | 30 | 0.400 |
50 | 4 | 30 | 0.133 |
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.
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