Name________________________
Date_________Period__________
How do Activity Level and Temperature Affect the Rate of
Cellular Respiration in Peas?
PRE-LAB- Read the introduction and procedure for the lab and then answer the following
questions. This pre-lab must be done in order for you to participate in the lab.
1. Write the balanced equation for cellular respiration.
2. How will the rate of cellular respiration be measured directly in this lab?
3. Name one other way that the rate of cellular respiration could be measured.
4. Why do we need to use “PV = nRT?” What does each term mean?
5. What is the purpose of using KOH? What would occur if it weren’t used?
6. Why will one of the vials contain both dry peas and glass beads?
7. For what duration will data be collected?
8. State a quantitative hypothesis for cellular respiration rate related to temperature of
environment.
9. State a quantitative hypothesis for cellular respiration rate related to temperature of
environment.
MORE PRELAB ON BACK
In the pictures below, label the contents that should be in each tube as well as how the
independent variable will be manipulated and how the dependent variable will be
measured. Draw in anything that is not already in the picture if necessary, such as
equipment, quantities or temperatures.
Temperature Positive Control Group
Peas
n non-absorbent
tton with KOH
Temperature Experimental Group
Peas
Cotton non-absorbent
Cotton with KOH
Activity Treatment Positive Control Group
Peas
n non-absorbent
tton with KOH
Peas
Cotton non-absorbent
Cotton with KOH
Activity Treatment Experimental Group
How do Activity Level and Temperature Affect the Rate of
Cellular Respiration in Peas?
Overview
In this laboratory you will measure oxygen consumption during respiration as the change in gas
pressure in respirometers (test tubes) containing either germinating or non-germinating peas. In addition,
you will determine the rate of cellular respiration of germinating peas due to changes in oxygen
consumption in a respirometer at two different temperatures.
Process-Based Target
A: Conduct an experiment and analyze the data to determine the effect of various factors on the rate of
cellular respiration using colorimeters and Logger Pro computer software.
Introduction
Respiration refers to two different but related processes. Respiration is the active acquisition of O2
by an organism and cellular respiration is the release of energy from organic compounds by metabolic
chemical oxidation within each cell.
Note the equation below for the complete oxidation of glucose. Oxygen is required for this energyreleasing process to occur.
C6H12O6 + 6 O2 ----> 6 CO2+ 6 H2O + 686 kcal of energy/mole of glucose oxidized (~38 ATP)
The chemical oxidation of glucose has important implications in relation to the measurement of
respiration. One could measure the:
1. Consumption of O2 during the oxidation of glucose (How many moles of O2 are consumed when
1 mole of glucose is oxidized?)
2. Production of CO2 during aerobic respiration (How many moles of CO2 are produced when 1
mole of glucose is oxidized?)
3. Consumption of O2 and the release of CO2 during cellular respiration (How many moles of CO2
are produced for every mole of O2 consumed?)
In this experiment, the relative volume of O2 consumed by germinating and non-germinating (dry)
peas at two different temperatures will be measured.
A number of physical laws relating to gases are important to the understanding of how the
apparatus that you will use in this exercise works. The laws are summarized in the general gas law that
states: PV = nRT
P is the pressure of the gas,
V is the volume of the gas,
n is the number of molecules of gas,
R is the gas constant (its value is fixed), and
T is the temperature of the gas.
This law implies the following important concepts about gases:
1. If temperature and pressure are kept constant, then the volume of the gas is directly proportional
to the number of molecules of the gas.
2. If the temperature and volume remain constant, then the pressure of the gas changes in direct
proportion to the number of molecules of gas present.
3. If the number of gas molecules and the temperature remain constant, then the pressure is inversely
proportional to the volume.
4. If the temperature changes and the number of gas molecules remain constant, then either pressure
or volume (or both) will change in direct proportion to the temperature.
5. Gases and fluids flow from regions of high pressure to regions of low pressure.
In this experiment, the CO2 produced during cellular respiration will be removed in the presence of
potassium hydroxide (KOH) and will form solid potassium carbonate (K2CO3) by the following reaction:
CO2 + 2KOH  K2CO3 (s) + H2O (l)
Therefore, the change in the volume of gas in the respirometer will be directly related to the amount of
oxygen consumed. In the experimental apparatus (Figure 5.1), if water temperature and volume remain
constant, the water will move toward the region of lower pressure due to the consumption of O2. The vial
with glass beads only will permit detection of any changes in volume due to atmospheric pressure changes
or temperature changes.
The amount of O2 consumed will be measured over a time course. The experiment requires four
respirometers to be constructed. However, each student pair will only be responsible for TWO
respirometer tubes depending upon the portion of the experiment they were assigned.
Experiment
Water Bath
Temp.
Contents of Respirometer
Temperature
Treatment
(Positive Control
Group)
Warm Water
(Room Temp
~25oC)
Temperature
Treatment
(Experimental Group)
Cold Water
(~10oC)
Activity Treatment
(Positive Control
Group)
Warm Water
(~25oC)
Germinating Seeds, KOH, NonAbsorbent Cotton, Absorbent
Cotton
Activity Treatment
(Experimental Group)
Warm Water
(~25oC)
Dry Seeds + Beads to Equalize
Volume, KOH, Non-Absorbent
Cotton, Absorbent Cotton
Name of Person
Responsible for
Setting Up Tube
Germinating Seeds, KOH, NonAbsorbent Cotton, Absorbent
Cotton, (Beads to equalize
volume)
Germinating Seeds, KOH, NonAbsorbent Cotton, Absorbent
Cotton, (Beads to equalize
volume)
Procedure: You will be sitting with a group of 4. However, students will work in pairs and perform
either the temperature experiment OR the seed activity experiment. You will then share data.
GOGGLES MUST BE WORN AT ALL TIMES.
Temperature Experiment Procedure:
1. The appropriate water baths have already been set up at your station. Do NOT pour out water from the
large, 1000mL beakers. One group member may have to pour out a small amount of water to the cold
water bath in order to make room for the addition of ice to bring the temperature of the bath to
approximately 10oC.
2. Obtain a 100mL graduated cylinder and fill it with ~50mL of H2O. Add 25 germinating peas and
determine the amount of water that was displaced (which is equivalent to the volume of the peas).
Record the volume of 25 germinating peas (subtract final volume with peas from initial volume of
water). Remove the germinating peas and place them on a paper towel.
You must perform step #2 TWICE because you need two test tubes which both contain 25
germinating pea seeds.
3. If the volume of the 25 germinating peas is not the same, then you must add glass beads to one (or
both) test tubes to make the pea seed volume equal in both tubes.
4. To assemble the respirometers, obtain 2 clean, dry test tubes. Place a small wad of absorbent cotton in
the bottom of each vial and, using a dropper, add 10 drops of 15% KOH to the absorbent cotton. Do
not drip KOH on the sides of the test tubes! Place a small wad of dry, non-absorbent cotton on top of
the KOH-soaked absorbent cotton. It is important that the amounts of cotton and KOH be the same for
each respirometer set up. Finally, add germinating peas. Refer to figure 5.1.
5. Attach the stopper apparatus from a gas pressure sensor box to each test tube. Note: Firmly twist the
stopper for an airtight fit. Submerge both vials into the appropriate water bath. Connect the plastic
tubing from the rubber stopper to a gas pressure sensor.
6. When BOTH test tubes are completely set up, you may fetch a computer:
a. The Gas Pressure Sensor (GPS) connected to the peas in the room temperature water bath
should be plugged into CHANNEL 1 of LabPro
b. The Gas Pressure Sensor (GPS) connected to the peas in the ice water bath should be plugged
into CHANNEL 2 of LabPro
7. Follow the directions in the pictures below and in Figure 5.3 to locate the LoggerPro software Cellular
Respiration Template file, to set the scale for your graphs, and to properly name your groups’ data files.
Double click on the top, left
“Experimental” graph. A “Graph
Options” window opens. Change the title
of the graph: WARM (x OC)
Germinating Peas & click “OK”.
Double click on the bottom left “Control”
graph. In the “Graph Options” window,
change title:
o
COLD (x C) Germinating Peas & click “OK”
Save data as a PDF: File menu Print “OK” PDF Save As PDF Save As:
Save your completed LoggerPro file as: ClassTrial#TEMP.cmbl 5b6Trial1TEMP.cmbl
OR 12aTrial4TEMP.cmbl
Seed Activity Experiment Procedure:
1. The appropriate water baths have already been set up at your station. DO NOT pour out water from the
large, 1000mL beakers. The temperature of both water baths should be the same.
2. Obtain a 100mL graduated cylinder and fill it with ~50mL of H2O. Add 25 germinating peas and
determine the amount of water that was displaced (which is equivalent to the volume of the peas).
Record the volume of 25 germinating peas (subtract final volume with peas from initial volume of
water). Remove the germinating peas and place them on a paper towel.
3. Refill the graduated cylinder with ~50mL of H2O. Drop 25 dry peas (non-germinating) into the
graduated cylinder and add enough glass beads to attain a volume equal to that of the larger,
germinating peas. Remove the dry peas and beads and place them on a paper towel.
4. To assemble the respirometers, obtain 2 clean, dry test tubes. Place a small wad of absorbent cotton in
the bottom of each vial and, using a dropper, add 10 drops of 15% KOH to the absorbent cotton. Do
not drip KOH on the sides of the test tubes! Place a small wad of dry, non-absorbent cotton on top of
the KOH-soaked absorbent cotton. It is important that the amounts of cotton and KOH be the same for
each respirometer set up. Finally, add germinating peas. Refer to figure 5.1.
5. Attach the stopper apparatus from a gas pressure sensor box to each test tube. Note: Firmly twist the
stopper for an airtight fit. Submerge both vials into the appropriate water bath. Connect the plastic
tubing from the rubber stopper to a gas pressure sensor.
6. When BOTH test tubes are completely set up, you may fetch a computer:
a. The Gas Pressure Sensor (GPS) connected to the germinating peas should be plugged into
CHANNEL 1 of LabPro
b. The Gas Pressure Sensor (GPS) connected to the dry, non-germinating peas should be plugged
into CHANNEL 2 of LabPro
7. Follow the directions below and in Figure 5.3 to locate the LoggerPro software Cellular Respiration
template file, to set the scale for your graphs, and to properly name your groups’ data files.
Double click on the top, left
“Experimental” graph. In the “Graph
Options” window, change the title:
Germinating Peas & click “OK”.
Double click on the bottom left “Control”
graph. In the “Graph Options” window,
change title:
Dry, Non-Germinating Peas & click “OK”.
Save data as a PDF: File menu Print “OK” PDF Save As PDF Save As:
Save your completed LoggerPro file as: ClassTrial#SEED.cmbl 5b6Trial2SEED.cmbl
OR 12aTrial3SEED.cmbl
FIGURE 5.1: Assembled Respirometer
FIGURE 5.2: Connecting Respirometer Test
Tubes to Gas Pressure Sensors
1
Peas
Cotton non-absorbent
Cotton with KOH
Figure 5.3: How to locate the LoggerPro cellular respiration pressure template file
A. Double click on Macintosh Hard Drive icon on desktop
B. Single click “Applications” folder
C. Scroll down and click on “Logger Pro 3” folder
D. Single click on “Experiments” folder
E. Scroll down & click on “Advanced Biology w Vernier” folder
F. Locate & double click to open “05 Cell Resp M4 Pressure.cmbl” file
G. Double click the large “change in pressure graph” on right.
•Click the Axes Option tab in “Graph Options” window.
•Change Y axis scale range: TOP: 1.000
BOTTOM: -10.000
Procedure for all groups
8. Allow all test tubes to equilibrate to the water temperature for ~5 minutes.
9. Click
to begin data collection. Maintain the temperature of the water bath during the course of
the experiment. Do not bump the water baths or the lab table while collecting data. The GPS are very
sensitive and may record the disturbance as a change in pressure.
10. Data collection will end after 20 minutes (or sooner as directed by your teacher). During this time, you
will do one of the following: get another computer and set up a Google Doc with your group. For
this, have one computer per group of 4, OR do the questions your teacher assigns. Your teacher will
tell you which option to do.
11. When you’ve completed the experiment and you’ve clean up your lab materials (do not pour out
water baths), you need to share your data with the teacher. Please click and drag your file to your jump
drive. Bring your drive to the instructor in order to download your lab data file to their computer.
Discussion—
GRAPH # 1-Go to the wiki, and find a graph that you like the best for the temperature
experiment and PRINT IT.
GRAPH #2-Go to the wiki and find a graph that you like the best for the activity
experiment and PRINT IT.
1. Explain the general relationship between pressure and time. How does change in pressure relate to
cellular respiration? CALCLUATE & USE RATE (∆P/ ∆t) to support your answer!
2. Explain the relationship between germination (vs. non-germination) and pressure change caused by
cellular respiration. CALCLUATE & USE RATE (∆P/ ∆t) to support your answer!
3. Explain the relationship between temperature of germinating peas (25oC and ~10oC) and pressure
changed caused by cellular respiration. CALCLUATE & USE RATE (∆P/ ∆t) to support your answer!
4. Identify ONE source of error related to experimental method or data collection method. Explain how
the error quantitatively affected results. Explain how to eliminate error for future experiments.
5. Create a title for this lab. Include the following terms: cellular respiration, oxygen consumption,
pressure change, temperature, seed activity, and RATE
 Use preferred format: Effect of ________ on ________ over __time__ to determine
______ for _Scientific name of peas_
Analysis Questions
1. Carbohydrates that we eat in plants and animal tissue must be hydrolyzed before they are used for
carbohydrate metabolism. Name TWO locations within our bodies and TWO enzymes that
accomplish carbohydrate hydrolysis? (HINT: use outside source and or textbook)
2. The first law of thermodynamics seems to conflict with what we know about ourselves. For example,
after strenuous exercise we run out of "energy". We must eat to replenish our energy stores. Where
has that energy gone? What form has it taken?
3. As a plant grows, not all of the carbohydrates produced by photosynthesis are stored as starch, nor are
they all respired to produce ATP. Name THREE cellular constituents would be synthesized from the
carbohydrates produced by photosynthesis?
___________________________________________________________________________
Post Lab Quiz-What you can bring and use on the post lab quiz:
1. GRAPH-Go to the wiki, and find a graph that you like the best for the temperature experiment and
PRINT IT.
2. GRAPH-Go to the wiki and find a graph that you like the best for the activity experiment and
PRINT IT.
3. PRE LAB-Look at your pre lab answers, and correct them.
4. ANSWERS TO DISCUSSION AND ANALYSIS-Must be handwritten in your writing, not typed,
not photocopied, and not on the iPad.