Pre-AP Biology Cellular Respiration Lab
Problem Is there a significant difference in the rate of respiration in mL of oxygen per minute per gram
(O2/min/g) for crickets and mealworms?
Procedure
1. Take the mass of the respirometers, and record the amounts in Table 1.
2. Add six crickets to one respirometer, nine mealworms to the second, and 5 glass beads to the third.
3. Re-seal the respirometers making sure that the seal is water proof around the glass pipette.
4. Take the mass of the respirometers that now contain the specimens. Record these masses in Table 1.
Use this mass and the original mass to determine the mass of the organisms.
5. Petroleum jelly should be lightly applied around the pipette to create a water-tight seal.
6. In order to acclimate the tubes to the temperature of the water, lay the respirometers into the water
bath with the end of the pipette out of the water for five minutes. This allows the air in the pipette to
cool to the temperature of the water. THIS IS EXTREMELY IMPORTANT. Do not skip this step.
7. At the end of the five minutes of acclimation, use a dropper to put a small amount of red dye at the tip
of the pipettes. This will let you easily see the water as it enters the pipette when the crickets and
mealworms are using oxygen.
8. Record your mL of oxygen consumed on Table 2 every 30 seconds.
9. Once the five minutes of measuring oxygen consumption is up, return the crickets and mealworms to
the holding containers.
10. You will use the information you have gathered to calculate the rate of oxygen consumption. See the
data and analysis page for instructions of how to calculate this rate.
11. Record your group’s rate on Table 3. You will collect this data from other groups once we have
completed the experiment.
Respirometer Assembly
Data and Analysis
Table 1:
Mass of Apparatus
Mass of Apparatus
+Organism
Mass of Organism
Cricket Apparatus
Mealworm Apparatus
Beads Apparatus
Table 2:
Time
(Min:Sec)
0:00
0:30
1:00
1:30
2:00
2:30
3:00
3:30
4:00
4:30
5:00
Oxygen Consumed
(mL) Crickets
Oxygen Consumed
(mL) Mealworms
0:00
0:30
1:00
1:30
2:00
2:30
3:00
3:30
4:00
4:30
5:00
Total Oxygen Consumed over five minutes (mL)
Crickets:
Mealworms:
Change in Volume
(mL) Glass Beads
0:00
0:30
1:00
1:30
2:00
2:30
3:00
3:30
4:00
4:30
5:00
Glass Beads:
Total Oxygen Consumed per minute: (mL) (5 minute total/5)
Crickets:
Mealworms:
Glass Beads:
Rate of Respiration: (mL O2/min/g)
Crickets:
Mealworms:
mL O2/min/gram =
Table 3:
Group
1
2
3
4
Glass Beads:
mL O2/min
Mass in grams
Respiration Rate of Crickets
Respiration Rate of Mealworms
Write the appropriate chemical equations:
Photosynthesis:
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Cellular Respiration: _________________________________________________________________
Analysis Questions:
1. Does there seem to be a difference between the rates of respiration of the two organisms? Explain.
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2. How is studying cellular respiration related to our previous study of photosynthesis and energy in
ecosystem food chains?
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3. How does our study of photosynthesis and cellular respiration relate to the interdependence observed
between organisms in nature?
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4. In this experiment, why was it necessary to first remove CO2 with the KOH before the consumption of O2
was measured?
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5. When a predator consumes its prey, it does so partly for the need of energy. We studied how electrons
are used at the end of the electron transport chain of respiration to make large amounts of ATP. Because
these electrons are used to make something that all organisms use for life processes, how could you
explain in your own words where these electrons originated and how they were made available in a form
useful to living things?
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