AP Biology: Laboratory
CELLULAR RESPIRATION
PRE-LAB –Read the traditional set-up for this lab (page 2) and the new set-up for this lab (pages 3-4), then
answer the following questions in your laboratory notebook.
1. Though the two labs follow different procedures, their purposes are the same. What is the purpose of both
of these experiments?
2. The traditional laboratory setup uses a tool
called a respirometer, shown in Figure 1 to the
right, to measure cellular respiration. What
piece of equipment does the new laboratory setup use in place of a respirometer?
3. According to Figure 1, what is the purpose of
using KOH in the traditional laboratory setup?
Figure 1
4. In the traditional experiment, the movement of food coloring in the pipette of the respirometer indicates a
change in the amount of what gas? Is the amount of this gas increasing or decreasing and why?
5. Which of the respirometers in the initial experiment is used as a control group? Explain your reasoning.
6. Imagine that a student doing the traditional experiment set up his respirometers, but forgot to add KOH to
the apparatus. What affect would this mistake have on the change in gas volume in the respirometer?
Explain why this would occur.
7. You will be performing the new set-up of this laboratory activity. Formulate a hypothesis for this
experiment.
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AP Biology: Laboratory
Traditional Lab Set-up
1. Obtain three (3) respirometers, 25 germinating peas, 25 non-germinating peas, glass beads and a 100-mL
graduated cylinder.
2. Prepare the contents of the respirometer:
a. For respirometer #1: Fill the graduated cylinder with 50-mL of H2O. Drop the 25 germinating peas
into the graduated cylinder to determine their volume. Record this number. Remove the peas and
put them on a paper towel.
b. For respirometer #2: Fill the graduated cylinder with 50-mL of H2O. Drop the 25 non-germinating
peas into the cylinder. Add enough glass beads to equal the volume of the germinating peas.
Remove the peas and beads and place them on a paper towel.
c. For respirometer #3: Fill the graduated cylinder with 50-mL of H2O. Add enough glass beads to
equal the volume of the germinating peas. Remove the beads and place them on a paper towel.
3. Assemble the respirometers by adding the components in the following order (be sure to keep the inside of
your respirometers as dry as possible):
a. A pellet of KOH
b. Small piece of cotton
c. Germinating peas in respirometer #1, non-germinating peas + beads in respirometer #2, glass beads
in respirometer #3.
4. Place a rubber stopper on each respirometer.
5. Place the respirometers into the water bath assigned
to you such that the glass pipette is on the tape as
shown in the figure to the right. Allow them to
equilibrate for 7 minutes.
6. Place a drop of food coloring into each pipette, then
place them in the water. Allow the respirometers to
equilibrate for another 3 minutes.
7. Record the initial location, in mL, of the food coloring in each respirometer(Time 0). This value will
indicate the amount of oxygen contained in the pipette at Time 0.
8. As oxygen is consumed by cellular respiration, the food coloring will move towards the chamber. Continue
to take readings every 5 minutes for 20 minutes. Record your data in Table 5.1.
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AP Biology: Laboratory
Investigation 1
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(g) 6 H2O + 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. Seeds undergo cell respiration during germination. Do seeds undergo cell
respiration before germination? Using your collected data, you will be able to answer the question regarding
respiration and non-germinating seeds.
OBJECTIVES
In this experiment, you will
 Measure gas production.
 Study the effect of temperature on cell respiration.
 Determine whether germinating peas and non-germinating seeds respire.
 Compare the rates of cell respiration in germinating and non-germinating seeds.
MATERIALS
 Lab Quest
 Computer
 Vernier CO2 gas sensor w/chamber OR
Vernier O2 gas sensor w/chamber
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25 germinating seeds
25 non-germinating seeds
Thermometer
PROCEDURE
Using the CO2 Gas Sensor OR O2 Gas Sensor, you will monitor the carbon dioxide produced or the oxygen
consumed by seeds during cell respiration. Both germinating and non-germinating seeds will be tested.
1. If your CO2 Gas Sensor has a switch, set it to the Low (0–10,000 ppm) setting. Connect the Gas Sensor to
Channel 1 of the Vernier computer interface.
2. Prepare the computer for data collection by opening the file “05 Cell Resp M2 CO2” or “05 Cell Resp M2
O2” (must match the gas sensor you are using) from the Advanced Biology with Vernier folder of
LoggerPro.
3. Obtain 25 germinating seeds 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 seeds into the respiration chamber.
5. Place the Gas Sensor into the chamber. Insert the sensor snugly into the grommet. If using the O2 Gas
Sensor, be sure it remains vertical throughout the experiment.
6. Wait four minutes for readings to stabilize, then begin collecting data by clicking “Collect.” Collect data for
ten minutes and click “Stop.”
7. When data collection has finished, remove the 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 anywhere on the graph to select it. Click the Linear Fit button, , to perform a linear
regression. A floating box will appear with the formula for a best fit line.
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AP Biology: Laboratory
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 seeds and place them in the respiration chamber
12. Repeat Steps 4–10 for the non-germinating seeds.
13. Collect data from a group using the gas sensor that you did not use. Record this in Table 2.
DATA
Table 1
Temperature (oC)
Condition
Room Temperature
Seeds
Table 2
CO2 rate of respiration
(ppt/min)
O2 rate of respiration
(ppt/min)
Germinating
Non-germinating
ANALYSIS – Answer in your laboratory notebook
1. Do you have evidence that cell respiration occurred in the seeds studied? Explain.
2. What is the effect of germination on the rate of cell respiration in the seeds studied? Cite specific data to
support your answer. Propose an explanation for any differences between cellular respiration in
germination and non-germinating seeds.
3. The rate of respiration was positive or negative, depending which gas was measured. Identify gas that
had a positive rate of change and the gas that had a negative rate of change. Explain why the rates are
positive or negative.
4. Imagine that you are given 25 germinating pea seeds that have been placed in boiling water for 5
minutes. You place these seeds in a gas chamber and collect data. Predict the rate of oxygen
consumption (i.e., cellular respiration) for these seeds, and explain your reasons.
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AP Biology: Laboratory
Investigation 2
In this part of the lab, you will design and conduct your own experiment to investigate the effect of temperature
and one factor of your choice on the rate of cellular respiration. The following materials are available to you:
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Computer
Lab Quest
Vernier CO2 gas sensor w/chamber OR
Vernier O2 gas sensor w/chamber
Thermometer
Balance
Seeds of varying species
Germinating seeds (6-day, 4-day, 1-day)
Non-germinating seeds
Ice
Boiling water
Crickets
Earthworms
1. Your lab group will be testing the effect of temperature and one factor of your choice on the rate of
respiration. You will test two different conditions within each factor. (NOTE: if your group’s second factor
includes live animals as either condition, you may NOT expose organisms to temperature conditions above
room temperature). Formulate a question and hypothesis that will be used as the basis for your experiment
to observe the rate of respiration when exposed to your chosen conditions.
Factor 1: Temperature
Factor 2:
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Condition 1:
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Condition 1:
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Condition 2:
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Condition 2:
Question (write in your laboratory notebook):
Hypothesis (write in your laboratory notebook):
Experimental Design
1. Design an experiment to investigate your hypothesis. Use the space below to write your materials and
procedure. When designing your experiment, be sure to address the following:
 What is the essential question being addressed?
 What assumptions are made about the question(s) being addressed? Can those assumptions be
verified?
 What factors need to be controlled in your experiment? How will you control these factors?
 What are possible sources of error in the experiment(s)?
2. Use the experimental design handout at the end of this packet to help plan your experiment.
3. Once you have completed step #1, see Ms. Chirby to present the plan for your experiment and receive
feedback and/or approval BEFORE you conduct it.
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AP Biology: Laboratory
Materials (rough draft below, final list in your lab notebook):
Procedure (rough draft below, final procedure in Googledoc and your lab notebook):
Data Collection (rough draft of data table below, final data table in lab notebook):
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AP Biology: Laboratory
Presentation and Evaluation of Results: You will be presenting your experiment as a formal lab report. Use
the information below to help you prepare your introduction, results and discussion sections.
Introduction:
 Provide background information on how the temperature conditions you selected are known to affect the
rate of cellular respiration in the organism(s) you tested.
Results:
 Table 1: raw data collected during the experiment
 Figure 1: a graph of CO2 production/O2 consumption rate versus temperature. Your graph will have
only four points, but you should include a key to distinguish between the two conditions for your second
chosen factor.
 Describe trends in the data.
 No calculations are required in the results section for this lab report.
Discussion and Conclusions:
 Discuss the relationship between temperature and the rate of respiration for each of the two conditions
for your second chosen factor.
 Determine whether your hypothesis is supported or refuted. Cite specific data from your table or figure
to support your claim.
 Discuss whether the data collected matches information from your introduction on the relationship
between temperature and cellular respiration in the organism(s) you tested.
 Discuss sources of non-human error in your experiment and explain ways to improve the experimental
design to eliminate these errors.
 Describe (specifically) a related experiment that could be done to expand your understanding of factors
that affect the rate of cellular respiration.
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