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Student Instruction Sheet
Challenge
See real-time evidence germinating seeds are engaged in cellular respiration.
Equipment and Materials
•
•
•
•
•
•
computer with USB port
PASPORT USB interface
PASPORT CO2 Gas Sensor
DataStudio software
Erlenmeyer flask, 250-mL
magnifying glass
• paper towel, 1 sheet
• beans or pea seeds (40)
• water, 100.0 mL
• Student Instruction Sheet
•
Student Response Sheet
Safety Precautions
Keep water away from electrical outlets, the computer,
the keyboard, and the PASPORT equipment!
Follow standard laboratory safety procedures.
Do not immerse the end of the CO2 Gas Sensor in water.
Background
When seeds become moist, and water penetrates into them, enzymes begin the
process of cellular respiration to provide the new plant with the fuel that it needs
for the building of new material. Cellular respiration is the process of oxidizing
food molecules such as sugar into carbon dioxide and water, producing energy-rich
molecules that fuel plant growth. Therefore, an increasing carbon dioxide (CO2)
concentration inside the flask with the germinating seeds is evidence that cellular
respiration is occurring as the seeds germinate.
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Predict
Before beginning the eLab, complete the prediction and vocabulary portions of
the Student Response Sheet.
Explore
Computer Setup
1. Plug the USB interface into the computer’s USB port.
To computer
2. Plug the CO2 Gas Sensor
into the USB interface.
This will automatically
launch the PASPortal
window.
3. Choose the appropriate DataStudio configuration file entitled
04 Cellular Respiration CF.ds
and proceed with the following instructions.
Configuration files automatically launch the appropriate
display(s), sampling rate(s), etc.
Note:
Equipment Setup
1. Fold a paper towel in half along its
length, and then fold it in half along its
width. Now the paper towel should
have 4 layers and be approximately
square in shape.
2. Place about 15-20 bean or pea seeds on the towel towards one edge of the
towel.
3. Fold about 1 inch of that edge of the towel over the
beans.
4. With the folded end on an outside edge, roll the towel
into a cylinder, trapping the beans inside. The cylinder will have
one open end and one nearly closed end.
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5. Slide the paper towel cylinder into the Erlenmeyer flask with the
closed end towards the bottom.
It is okay if a few beans (or seeds, if using pea seeds)
fall out during this procedure.
Note:
6. Slide the end of the CO2 Gas Sensor inside the
open end of the paper towel. Firmly plug the
opening of the flask with the rubber stopper of
the CO2 Gas Sensor.
USB Link
Record Data
1. In DataStudio on the Experiment menu, click
Monitor Data. Monitor the data until the levels
of CO2 gas stabilizes.
The system will require a few
minutes to equilibrate. You should not need
to monitor the data longer than 5 minutes.
Avoid bumping the equipment, because
bumping or jarring will cause the CO2 Gas
Sensor to behave erratically.
CO
2
Gas Sensor
Note:
paper towel cylinder
containing bean seeds
2. When the CO2 gas readings stabilize, click the
Stop (
) button to stop monitoring.
3. Click the Start button (
recording data.
end of sensor is
inside paper cylinder
250-mL
Erlenmeyer flask
) to start
Note:
DataStudio has been set to record data at a rate of 1
sample every 15 seconds.
4. Record data for 20 minutes. Click the Stop button.
This data will be stored in Run 1. Make a note in your
data table on your Student Response Sheet that Run 1 is data
collected from dormant bean seeds.
Result:
5. Carefully remove the CO2 Gas Sensor from the flask and add 100.0 mL of
water to the flask.
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6. Carefully insert the CO2 Gas Sensor into the flask as before, sealing the top
of the flask with the rubber stopper.
7. Click the Start button to begin recording data.
8. Leave this setup alone and allow data recording to proceed for 24 hours.
9. After 24 hours, Stop recording data.
This data will be stored in Run 2. Make a note in your
data table on your Student Response Sheet that Run 2 is data
collected from germinating seeds.
Result:
Analyze
1. Carefully remove the CO2 Gas Sensor from the flask and return it to its
storage bag.
2. Pull the paper towel/seed package out of the flask.
3. Use the magnifying glass to observe the seeds.
4. Record your observations on the Student Response Sheet.
5. Record the concentration of CO2 gas at the beginning and end of the data Run
#1.
Expand the scale and move the position of the x- and yaxes until you can easily see all the data. To rescale an axis of
the graph, hover the cursor over the axis until the rescale
symbol (
) appears, and click and drag the axis to rescale
it. To move the origin of the axis, hover the cursor over the
axis until the hand symbol ( ) appears, and then click and
drag the axis to move the desired range into view.
Hint:
6. Record the concentration of CO2 gas at the beginning and end of the data Run
#2.
7. Save your DataStudio file (on the File menu, click Save Activity As...) to the
location specified by your teacher.
8. Answer all questions on the Student Response Sheet.
9. Follow your teacher’s instructions regarding cleaning up your work space.
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Student Response Sheet
Name: ______________________________
Date:_______________________________
No Respiration for the Weary
Vocabulary
Use available resources to find the definitions of the following terms:
adenosine diphosphate (ADP):______________________________________
___________________________________________________________
adenosine triphosphate (ATP): _____________________________________
___________________________________________________________
carbon dioxide (CO2): ___________________________________________
___________________________________________________________
cellular respiration: _____________________________________________
___________________________________________________________
germination: __________________________________________________
___________________________________________________________
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Predict
What do you think will happen to the seed after 24 hours of being in a moist
environment? What do you think will happen to the level of CO2 inside the flask?
____________________________________________________________
____________________________________________________________
____________________________________________________________
____________________________________________________________
Data
Data
Run
Condition
of seeds
Appearance
of seeds
Concentration of CO2
(ppm)
Before Run
After Run
1
2
Draw a sketch of your graph of CO2 concentration. Label the x- and y- axes, and
show the portion that represents time when seeds were dormant and time when
seeds were germinating.
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Analyze
1. Describe your graph.
____________________________________________________________
____________________________________________________________
____________________________________________________________
2. Did your observation of the levels of CO2 after you added water to the flask
match your expectations? Why or why not?
____________________________________________________________
____________________________________________________________
____________________________________________________________
3. In your own words, explain why the levels of CO2 changed the way they did
after you added water to the flask.
____________________________________________________________
____________________________________________________________
____________________________________________________________
Synthesize
1. Find an expression (formula) in your textbook that summarizes the net
molecular changes occurring in cellular respiration, and write the expression
here.
____________________________________________________________
____________________________________________________________
____________________________________________________________
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2. Judging from this expression, what gaseous molecule would you expect to be
produced during cellular respiration?
____________________________________________________________
____________________________________________________________
____________________________________________________________
3. If cellular respiration occurs during germination, what would you expect would
happen to the levels of CO2 inside the flask after you added water?
____________________________________________________________
____________________________________________________________
____________________________________________________________
4. Was your prediction correct? Why or why not?
____________________________________________________________
____________________________________________________________
____________________________________________________________
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