AP Lab 5 Cell Respiration
(O2 Gas Sensor)
Name: __________________
Background
Cell respiration refers to the process of converting the chemical energy of organic molecules into a form
immediately usable by organisms. Glucose may be oxidized completely if sufficient oxygen is available
according to the following equation:
C6H12O6 + 6O2 > 6 H2O + 6 CO2 + energy (686 kcal/mole)
All organisms, including plants and animals, oxidize glucose for energy. Often, this energy is used to convert
ADP and phosphate into ATP. Peas undergo cell respiration during germination. Do peas undergo cell
respiration before germination? Additionally, as we have learned before, temperature can also affect biological
processes and the rates at which they occur. Using your collected data, you will be able to answer two
questions at the completion of this lab:
• Do non-germinating (dormant) peas respire? If so, at what rate?
• Does temperature affect the respiration rate of germinating peas?
By studying the equation for cellular respiration shown above, you should notice that there are 3 ways that
cellular respiration could be measured. One could measure the:
• Consumption of O2 (how many moles of oxygen are consumed in cellular respiration?)
• Production of CO2 (how many moles of carbon dioxide are produced in cellular respiration?)
• Release of energy during cellular respiration
OBJECTIVES
In this experiment, you will:
• Measure oxygen gas.
• Study the effect of temperature on cell respiration.
• Determine whether germinating peas and non-germinating peas respire.
• Compare the rates of cell respiration in germinating and non-germinating peas.
MATERIALS
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25 germinating peas
25 non-germinating peas
Vernier computer interface
250 mL respiration chamber
Vernier O2 Gas Sensor
ice cubes
two 100 mL beakers
thermometer
PROCEDURE
Part I: Respiration in germinating peas vs. non-germinating peas
1. Connect the O2 Gas Sensor to the computer interface.
2. Obtain 25 germinating peas and blot them dry between two pieces of paper towel. Use the thermometer to
measure the room temperature. Record the temperature in Table 1.
3. Place the germinating peas into the respiration chamber.
4. Place the O2 Gas Sensor into the bottle as shown in Figure 1. Gently push the sensor down into the bottle
until it stops. The sensor is designed to seal the bottle without the need for unnecessary force.
Figure 1
5. Wait two minutes, then begin collecting data. Record the readings for oxygen gas in your data table every
minute for 10 minutes.
6. When data collection has finished, remove the O2 Gas Sensor from the respiration chamber. Place the peas in
a 100 mL beaker filled with cold water and an ice cube.
7. Fill the respiration chamber with water and then empty it. Thoroughly dry the inside of the respiration
chamber with a paper towel.
8. Obtain 25 non-germinating peas and place them in the respiration chamber
9. Repeat Steps 4–7 for the non-germinating peas.
Part II: Respiration of germinating peas in different temperatures
10. Remove the germinating peas from the cold water and blot them dry between two paper towels.
11. Repeat Steps 3–7 to collect data with the germinating peas at a cold temperature.
ANALYSIS
1. Make a graph showing the results of the experiment. All data collected should be displayed on one graph.
Be sure to clearly label both axes (don't forget units), used different colors and give a key as needed, use
appropriate scaling on both axes, and provide an appropriate title. "Cell Respiration Lab" is NOT an
appropriate title.
CONCLUSION
2. Describe the relationship between the amount of oxygen consumed and time.
3. What is the effect of germination on the rate of cell respiration in peas? Explain.
4. What is the effect of temperature on the rate of cell respiration in peas? Explain.
5. Why do germinating peas undergo cell respiration?
6. If you used the same experimental design to compare the rates of respiration of a 25g reptile and a 25g
mammal at 10 deg. Celcius (chilly), what results would you expect? Explain your reasoning.
7. If respiration of a mammal were studied at both room temperature (21 deg. C) and chilled (10 deg. C) what
results would you expect? Explain your reasoning.
8. Why did you have to use 25 peas?
EXTENSIONS:
Design an experiment for each of the following investigations:
1. Compare the respiration rate among various types of seeds.
What types of seeds would you use?
How many of each?
What is your IV?
What is your DV?
Would you have a control treatment? If so, what?
What should you hold constant?
Describe your procedure:
Create a data table for the experiment.
Make a hypothesis about your results:
2. Compare the respiration rate among seeds that have germinated for different time periods.
What type of seeds would you use?
How many in each treatment?
What different time periods of germination would you compare?
What is your IV?
What is your DV?
Would you have a control treatment? If so, what?
What should you hold constant?
Describe your procedure:
Create a data table for the experiment.
Make a hypothesis about your results:
3. Compare the respiration rate among various types of small animals, such as insects or earthworms.
What type of animals would you use?
How many of each?
What is your IV?
What is your DV?
Would you have a control treatment? If so, what?
What should you hold constant?
Describe your procedure:
Create a data table for the experiment.
Make a hypothesis about your results: