NAME: ____________________________________ DATE: ____________ BLOCK: ____
Cellular 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 by the following equation:
C6H12O6 + 6O2 (g)
2O
+ 6 CO2 (g) + energy
All organisms, including plants and animals, oxidize glucose for energy. Often, this energy is
used to convert ADP and phosphate into ATP. It is known that peas undergo cellular
respiration during germination. Do peas undergo cellular respiration before germination?
The results of this experiment will verify that germinating peas do respire. Using your
collected data, you will be able to answer the question concerning respiration and nongerminating peas.
Using the O2 Gas Sensor, you will monitor the oxygen consumed by peas during cellular
respiration. Both germinating and non-germinating peas will be tested. Additionally, cellular
respiration of germinating peas at two different temperatures will be tested.
OBJECTIVES
In this experiment, you will

Use an O2 gas sensor to measure concentrations of oxygen.
 Study the effect of temperature on cellular respiration.
 Determine whether germinating peas and non-germinating peas respire.
 Compare the rates of cellular respiration in germinating and non-germinating peas.
Figure 1
MATERIALS
Vernier computer interface
Logger Pro
Vernier O2 Gas Sensor
25 germinating peas
25 non-germinating peas
250-mL respiration chamber
ice cubes
1-L beaker
Thermometer
Two 100-mL beakers
PROCEDURE
1. Prepare the computer for data collection by opening the file in the Experiment 11A folder
of Biology with Computers.
2. Plug the O2 Gas Sensor into Port 1 of the Vernier computer interface.
3. 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.
4. Place the germinating peas into the respiration chamber.
5. 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.
6. Wait two minutes, and then begin collecting data by clicking
collected for 10 minutes.
Collect
. Data will be
7. When data collection has finished, remove the O2 gas sensor from the respiration
chamber.
8. Fill the respiration chamber with water and then empty it. Thoroughly dry the inside of
the respiration chamber with a paper towel.
9. Determine the rate of respiration:
a. Click the Regression button, , to perform a linear regression. A floating box will
appear with the formula for a best-fit line.
b. Record the slope of the line, m, as the rate of respiration for germinating peas at
room temperature in Table 2.
c. Close the linear regression floating box.
10. Move your data to a stored run. To do this, choose Store Latest Run from the
Experiment menu.
11. Obtain 25 non-germinating peas and place them in the respiration chamber.
12. Repeat Steps 5 – 10 for the non-germinating peas. While you wait for 10 minutes
collecting data, put the germinating peas in a 100-mL beaker filled with cold water and
ice cubes for approximately 10 minutes.
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13. Use the thermometer to measure the water temperature of the beaker containing the
germinating peas. Record the water temperature in Table 1.
14. Take the germinating peas out of the ice water and blot them dry.
15. Put the dried, cold germinating peas in the respiration chamber.
16. Repeat Steps 5 – 10 to collect data with the germinating peas at a cold temperature.
While you wait for 10 minutes collecting data, put the nongerminating peas in a 100-mL
beaker filled with cold water and ice cubes for approximately 10 minutes.
17. Use the thermometer to measure the water temperature of the beaker containing the
nongerminating peas. Record the water temperature in Table 1.
18. Take the nongerminating peas out of the ice water and blot them dry.
19. Put the dried, cold non-germinating peas in the respiration chamber.
20. Repeat Steps 5 – 10 to collect data with the non-germinating peas at a cold temperature.
21. Draw your graph in the box provided below. Be sure to label your axes and may a key
for your four lines.
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DATA
TABLE 1
Condition
Temperature (°C)
Room
Cold water
TABLE 2
Peas
Rate of Respiration (%O2/min)
Germinating at room temperature
Non-germinating at room
temperature
Germinating at cool temperature
Non-germinating at cool
temperature
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QUESTIONS
1. Do you have evidence that cellular respiration occurred in peas? Explain your answer.
2. What is the effect of germination on the rate of cellular respiration in peas?
3. What is the effect of temperature on the rate of cellular respiration in peas?
4. Why do germinating peas do cellular respiration?
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5. If you used the same experimental design to compare the rates of respiration of a 25gram reptile and a 25-gram mammal, what results would you expect? Explain your
answer in terms of warm and cold temperatures.
6. If respiration in a small mammal was studied at 21C(room temperature), 10C (a cold
winter day) and -5C (below freezing), what results would you predict? Explain your
answer.
7. If you set up an experiment to test the rates of cellular respiration in peas that have been
germinating for 0, 24, 48, and 72 hours, what results would you expect? Explain your
answer.
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