Activity 02
PS-2820
Respiration of Germinating Seeds
Biology: Respiration, germination
Qty
1
1
1
1
1
1L
1
1
40
1L
DataStudio GLX setup file: seeds.glx
Equipment and Materials
PASPORT Xplorer GLX
PASPORT CO2 Gas Sensor
PASPORT Extension Cable
Sampling Bottle (included with the sensor)
Beaker, 1000 mL
Ice, cube or crushed
Magnifying glass
Paper towel
Pea (or bean) seeds
Water
Part Number
PS-2002
PS-2110
PS-2500
SE-7288
Purpose
The purpose of the activity is to compare the production of carbon dioxide gas by germinating
seeds with the production of carbon dioxide gas by dormant seeds. Also, determine the effect of
temperature on seed germination.
Background
Dormant seeds contain all the materials required to start new plant growth including starches,
enzymes, DNA to guide the process, RNA, and all the necessary cellular machinery. They need
water and oxygen to start the process called germination, which is the process of initiating new
plant growth from a seed.
When seeds become moist, the water is first absorbed by the seed’s covering, which softens and
allows water to penetrate the seed. As soon as the cells inside the seed absorb the water, the
enzymes, which must be suspended in water to function, begin the process of cellular respiration
to provide the new plant with energetic adenosine triphosphate (ATP) molecules that it needs to
fuel the building of new plant material.
The process of cellular respiration converts sugar and oxygen and other substances into ATP,
water, and carbon dioxide gas. Therefore, carbon dioxide gas production is evidence of cellular
respiration in germinating seeds.
Pre-Lab Setup (24 hours in advance)
Place 20 seeds in the center of a paper towel. Fold the towel over to cover the seeds. Carefully
place the folded towel and seeds in the bottom of a beaker, and soak the paper towel with water
so that the seeds will begin to germinate. Put the beaker in a dark location (for example, inside a
cabinet) for 24 hours.
Pre-lab Questions
Compare dormant seeds and germinating seeds.
1.
How will germinating seeds look compared to dormant seeds?
1.
How will the amount of carbon dioxide gas given off by dormant seeds compare to the
amount of carbon dioxide gas given off by germinating seeds?
Biology with Xplorer GLX
© 2005 PASCO
p. 9
Activity 02
Respiration of Germinating Seeds
PS-2820
1.
How will the amount of gas given off by cold germinating seeds compare to the amount of
gas given off by warm (room temperature) seeds?
1.
What other conditions beside temperature might affect the rate of production of gas by
germinating seeds?
Safety Precautions
•
Follow all directions for using the equipment.
•
Wear protective gear (e.g., safety goggles, gloves, apron).
Procedure
GLX Setup
1.
Connect a PASPORT Extension Cable into Port 1 on the
top of the Xplorer GLX. Connect the other end of the
Extension Cable to the PASPORT CO2 Sensor.
•
The Graph Screen will automatically open with CO2
Concentration (ppm) versus Time (s).
1.
Open the GLX setup file labeled seeds.glx (check the
Appendix at the end of this activity). The file is set to
record data once per second.
Sensor Calibration (Optional)
•
Figure 1: Connect sensor to GLX
See the appendix at the end of this activity.
Equipment Setup
1.
Put 20 dry, dormant seeds into the sampling bottle.
1.
Put the end of the CO2 Gas Sensor into the sampling bottle. Firmly plug
the end of the sampling bottle with the rubber stopper.
•
Note: Avoid bumping the equipment because jarring or bumping the CO2
Gas Sensor may cause it to record erratically.
Record Data: Dormant Seeds
1.
Press the Start key
on the GLX.
1.
Record data for 20 minutes and then stop.
1.
Remove the seeds from the sampling bottle and examine them closely.
Write a description of how they look in the Lab Report section.
Figure 2: Sensor and
sampling bottle
Record Data: Germinating Seeds
1.
Put 20 germinating seeds into the sampling bottle. Put the CO2 Gas Sensor into the bottle
so that the rubber stopper firmly plugs the end of the bottle.
1.
Press the Start key
1.
Record data for 20 minutes and then stop.
Biology with Xplorer GLX
on the GLX.
© 2005 PASCO
p. 10
Activity 02
1.
Respiration of Germinating Seeds
PS-2820
Remove the CO2 Gas Sensor temporarily.
Record Data: Ice Water Bath
1.
Fill a large beaker about half full of water and add about half a liter of cubed or crushed
ice.
1.
Return the CO2 Gas Sensor to the sampling bottle so that the rubber stopper firmly plugs
the end of the bottle.
1.
Put the sampling bottle into the ice water in the beaker and hold the neck of the sampling
bottle so that most of the bottle remains in the ice water.
1.
After about a minute, press the Start key
1.
Record data for 20 minutes and then stop.
1.
Remove the sampling bottle from the ice water and dry the outside of the bottle.
1.
Remove the seeds from the sampling bottle and examine them closely. Write a description
of how the germinating seeds look in the Lab Report section.
1.
Follow instructions for disposing of materials and putting away the equipment.
on the GLX.
Analysis
1.
Draw a sketch of your CO2 Concentration versus Time graph as requested in the Lab
Report section.
1.
Use your recorded data to find the change in CO2 concentration for the dormant seeds, the
germinating seeds, and the germinating seeds at a low temperature.
•
In the Graph Screen, press F3 to open the ‘Tools’ menu. Select ‘Statistics’ and press
‘Activate’. The Statistics show the minimum and maximum values.
1.
Calculate the rate of change of CO2 concentration versus time, or the ratio of CO2
concentration (in ppm) divided by the time (in grams), for each run of data.
How do your results compare with others in your class?
Record your results in the Lab Report.
Biology with Xplorer GLX
© 2005 PASCO
p. 11
Activity 02
Respiration of Germinating Seeds
PS-2820
Appendix:
To open a specific GLX file, go to the home screen (press
). In the home
screen, select ‘Data Files’ and press ‘Activate’ (
). Use the cursor keys to
navigate to the file you want. Press F1 ( ) to open the file.
Data Files Icon
To calibrate the PS-2110 CO2 Gas Sensor, see the instructions
provided by the instructor.
Biology with Xplorer GLX
© 2005 PASCO
p. 12
Activity 02
Respiration of Germinating Seeds
PS-2820
Lab Report - Activity 02: Respiration of Germinating
Seeds
Name ________________________________ Date ___________
Pre-Lab Questions
Compare dormant seeds and germinating seeds.
1.
How will germinating seeds look compared to dormant seeds?
1.
How will the amount of carbon dioxide gas given off by dormant seeds compare to the
amount of carbon dioxide gas given off by germinating seeds?
1.
How will the amount of gas given off by cold germinating seeds compare to the amount of
gas given off by warm (room temperature) seeds?
1.
What other conditions beside temperature might affect the rate of production of gas by
germinating seeds?
Data
Description of Seeds
Dry, dormant seeds
Biology with Xplorer GLX
Germinating seeds
© 2005 PASCO
p. 13
Activity 02
Respiration of Germinating Seeds
PS-2820
Data
Make a sketch of one run of CO2 Concentration versus Time, including labels for the y- and xaxes.
Data Table
Run
Initial CO2
concentration
Final CO2
concentration
Total time
Rate of CO2
production
Dry, dormant seeds
Germinating seeds
Cold germinating seeds
Questions
1.
How does the rate of CO2 production for germinating seeds compare to the rate of CO2
production for the dry, dormant seeds?
2.
How does the rate of CO2 production for cold germinating seeds compare to the rate of
CO2 production for the room temperature germinating seeds?
3.
How does the appearance of the germinating seeds compare to the appearance of the dry,
dormant seeds?
Biology with Xplorer GLX
© 2005 PASCO
p. 14