Aerobic Cell Respiration _____ / 22 = _____%
Names:
Date:
Class:
The cells of all living organisms require a constant supply of energy to carry out the many
functions necessary for life. The molecule used to provide energy is ATP (adenosine triphosphate). The major source of ATP for all cells is the oxidation of glucose, via the process of
cell respiration. The initial steps of cell respiration, called glycolysis, occur in the cells of all
organisms.
For most organisms, the process of cell respiration is an oxygen-consuming process.
Following glycolysis, a process that occurs in the cytoplasm, in which glucose is converted to
pyruvic acid, the Krebs cycle and electron transport chain occur in the mitochondria. CO2 is
given off during the Krebs cycle and the hydrogen electrons removed from the pyruvic acid
backbone are transferred to the electron carriers NADH and FADH2. These electrons are then
passed through the electron transport chain to power the movement of hydrogen ions against a
concentration gradient. Without oxygen, which functions as the final electron acceptor in the
electron transport chain, the process of aerobic respiration cannot happen. For each glucose
molecule oxidized, 36 - 38 ATP are produced. Most organisms cannot survive without aerobic
respiration.
The chemical reaction for aerobic respiration is:
C6H12O6 + 6O2

6CO2 + 6H2O + 36 ATP
During aerobic respiration oxygen gas is consumed and carbon dioxide gas is produced.
In this laboratory exercise we will measure the concentration of carbon dioxide gas (using the
CO2 Gas Sensor) in a sealed plastic jar (the Respiration Chamber) that contains the sample to
be tested (either germinating beans or non-germinating beans). If respiration occurs, the
concentration of carbon dioxide gas will increase. You will see this as an increase in ppm (parts
per million) recorded on the computer screen. Germination is the process of seeds developing
into new plants. Germination is a process when the seed develops into a seedling. The seeds
that germinate have an embryo inside it that grows into a new plant. The process of germination
starts with the seed absorbing water. The absorption of water activates an enzyme that increases
respiration. The plant cells divide rapidly and the embryo inside the seed becomes large, and the
radical (first root) of the plant emerges from the seed coat
This exercise will be performed at three different temperatures (ice water: 4 – 12°C, room
temperature: 20 – 22°C and warm temperature: 35 – 40°C). I will assign one temperature per lab
group. Each lab group will do 3 trials at their assigned temperature with non-germinating and with
germinating beans.
The data from the entire class will be collected for analysis. You will need to record the
data from all groups. During this laboratory exercise you will study the effect of temperature on
cellular respiration.
Problem: What is the difference in carbon dioxide production between germinating beans
and non-germinating beans? Will temperature have an effect on cellular respiration rates?
Hypothesis: (if/then statement) (1pt)
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Materials Required For Each Laboratory Table:
Computer
Vernier Interface and Power Supply
CO2 Gas Sensor
250-ml Respiration Chamber
15 Germinating beans
15 Non-germinating beans (dormant peas)
Two 100-ml Beakers
Thermometer
Hot Plate (35oC - 40oC)
Ice Bath
Procedure:
1. Hook up the vernier hardware to the power source and the computer, and
connect the CO2 chamber to channel one of the vernier.
2. Log in to the laptop and search logger pro.
3. When logger pro opens it should read the CO2 monitor and you should see
CO2 on the y axis measuring from 0 to 5000ppm, and time from 0-5 minutes
on the x axis. If you do not see this, click on experiments, set up sensors,
show all sensors, and click on channel one, select CO2 gas.
4. If time is not set to 5 minutes do the following: click experiment, data
collection, and set the length to 5 minutes. In this same window change the
sample/minutes to read 6 samples per minute.
5. Obtain 15 non-germinating beans. Place them into the respiration chamber.
6. For the room temperature measurements, use a thermometer to measure
room temperature. For hot and cold temperatures, prepare a water bath of
the correct temperatures (ice water 4-12 C, warm water 35-40 C)
7. Put the respiration container containing the beans into this water bath. Let
the chamber sit for at least 3 minutes so the beans will be at the correct
temperature. Do not allow water from the water bath to enter the respiration
chamber.
8. Use a thermometer to measure the temperature of the sample you are
collecting (either the air temperature or the temperature of the water bath)
containing the non-germinating beans. Record the temperature in Table 1.
9. Place the shaft of the CO2 gas sensor in the opening of the respiration
chamber. Gently twist the top of the stopper on the shaft of the CO2 gas
sensor into the chamber opening. Do not twist the shaft of the CO2 gas sensor
or you may damage it.
10. Wait one minute, and then begin measuring carbon dioxide by clicking the
green play button. Data will automatically be collected for 5 minutes. The
button will automatically read stop (or turn red) after 5 minutes. Do not click
stop this is a toggle button.
11. Remove the CO2 gas sensor from the respiration chamber. Use a notebook or
notepad to fan air across the openings in the probe shaft of the CO2 gas
sensor for 1 minute. Fan air over the respiration chamber to allow excess
CO2 inside to escape.
12. To determine the rate of cellular respiration, click the linear fit line
icon in the toolbar at the top of the screen, record the slope of the line m
as the rate of respiration at the selected temperature in Table 2. Note:
You will record the “m” number displayed – this is the rate of change in
ppm/min
13. Repeat steps 6-12 for your selected temperature for each of your 3 trials.
14. Erase your data before making another run. When you start a new run the
computer will ask you if you wish to save your data – You do not need to save
your data, so respond “Erase and Continue.”
15. Remove the non-germinating beans. Obtain 15 germinating beans, blot them
dry between two pieces of paper towel and place them in the respiration
chamber.
16. Repeat steps 6-12 for the germinating beans at the temperature you have
been assigned for 3 trials.
Table 1 Temperature Used
(data from the entire class) (1 point)
Condition
Temperature ( °C)
Cold Trial
Room Trial
Hot Trial
Table 2 – Rate of Respiration (ppm/min) in Beans
(data from the entire class) (3 points)
Temperature
Germinating Beans
Non-Germinating Beans
Trial 1 Trial 2
Trial 3
Avg
Trial 1 Trial 2
Trial 3
Avg
Cold Temperature Group
Room Temperature
Group
Hot Temperature
Group
Analysis: (answer on a separate sheet of paper)
1. Make a bar graph of the data from the data table (rate of respiration vs.
temperature) (5 points) Use the averages in your graph. You must have a
scale on both axes.
2. What evidence if any do you have that cellular respiration occurs in beans?
Be sure to use data to prove your answer. (2 points)
3. Compare the cellular respiration rates in germinating and non-germinating
beans. Be sure to use data in your answer. (2 points)
4. Why did the germinating beans have a different rate of cellular respiration
than the non-germinating beans? Use your notes on cellular respiration. (2
points)
5. What is the effect of temperature on the rate of cellular respiration of beans?
Be sure to use data in your answer. (2 points)
6. Why do beans undergo the process of cellular respiration? (1 point)
7. Explain each step of cellular respiration – where it occurs, what goes in, and
what comes out. (3 points)