AP Biology
updated Jan. 2010
Cellular Respiration Lab
Cellular Respiration – Adapted from Laboratory 5 in AP Student Manual
Introduction: Cellular respiration is the release of energy from organic compounds by
metabolic chemical oxidation in the mitochondria within each cell. Cellular respiration
involves a series of enzyme-mediated reactions. The equation below shows the complete
oxidation of glucose. Oxygen is required for this energy-releasing process to occur.
C6H12O6 + 6O2 -----> 6 CO2 + 6 H2O + 686 kilocalories of energy /mole of glucose oxidized
By studying the equation above, you will notice there are three ways cellular respiration
could be measured. One could measure the:
1. Consumption of O2 (How many moles of oxygen are consumed in cellular respiration?)
2. Production of CO2 (How many moles of carbon dioxide are produced by cellular
respiration?)
3. Release of energy during cellular respiration.
Objectives
calculate the rate of cell respiration from experimental data.
relate gas production to respiration rate; and
test the effect of temperature on the rate of cell respiration in nongerminated
versus germinated seeds in a controlled experiment.
In this experiment, the relative amount (ppm) of CO2 produced by germinating and
nongerminating (dry) peas at two different temperatures will be measured.
Overview: In this experiment, you will work with seeds that are living but dormant. A seed
contains an embryo plant and a food supply surrounded by a seed coat. When the necessary
conditions are met, germination occurs, and the rate of cellular respiration greatly
increases.
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. Therefore, an increase in (CO2) concentration inside
the flask with the germinating seeds is evidence that cellular respiration is occurring as
the seeds germinate.
In this experiment you will measure carbon dioxide production during germination. You will
measure the change in gas production in respirometers containing either germinating or
nongerminating pea seeds. In addition, you will measure the rate of respiration of these
peas at two different temperatures.
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AP Biology
updated Jan. 2010
Cellular Respiration Lab
The amount of carbon dioxide will be measured in __ minute intervals (tbd), over a period
of 20 minutes. Four respirometers should be set up as follows:
Respirometer Temperature
Contents
1
Room
Germinating seeds
2
Room
Dry Seeds
3
0
10 C
Germinating Seeds
4
0
Dry Seeds
10 C
FIRST: write down your hypotheses! What do you predict will happen and why?
Materials
Computer with USB ports
PASPORTtm
USB link
PASPORTtm
CO2 Gas sensor
250 mL Erlenmeyer flasks
Pea seeds (dry and germinated)
Cold water bath
thermometers
Procedure
1. Prepare a room-temperature station (approx. 25 degrees Celsius) and a cold-water bath
(approx. 10 degrees Celsius).
2. Count out 100 germinating peas and 100 nongerminating peas and put into two separate
250 mL Erlenmeyer flasks. To assemble respirometers, insert the stopper with the CO2
sensor into each flask mouth to get a tight seal.
3. Using the same procedure as in the previous step, to assemble 2 more respirometers*.
These will go into the 10-degree bath.
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AP Biology
updated Jan. 2010
Cellular Respiration Lab
*This can be done in two sets, at different temperatures, if space or time is limited.
8. Connect the CO2 sensors to the USB ports of a computer using the USB link and allow
the respirometers an equilibration period of 1 minute before taking measurements.
Respirometers 1 and 2 should be kept at room temperature bath, and the other two should
be in the 10 degree bath.
9. After equilibration, take an initial CO2 measurement, after which a reading should
be taken every 5 minutes for a period of 20 minutes. Check the temperature and
record all data. This collective data should be displayed in table form in your
report (Table 5.1). A graph (Graph 5.1) should display these data.
Results:
a. Table 5.1: Measurement of CO2 Production by Germinating and Dry Pea Seeds
at Room Temperature (___0C) and 100C in ppm.
b. Graph 5.1 : the results for respiration of the peas at both room temperature
and 10 0C.
c. Table 5.2 : From the slope of the four lines on the graph, determine the
overall rate of CO2 Production of germinating and dry peas during the experiments
at room temperature and 100C. Recall that rate = Δ Y/ Δ X. See below.
Table 5.2 Rate of CO2 Production
Condition
Germinating Peas/100C
Show Calculations Here
The house is red and
sometimes blue
Germinating peas /Room The house is red and somue
Temperature
sometimes blue
Rate in ppm CO2 / min
The house is red and
sometimes blue
The house is red and
sometimes blue
Dry peas/100C
The house is red and
sometimes blue
The house is red and
sometimes blue
Dry Peas /Room
Temperature
The house is red and
sometimes blue
The house is red and
sometimes blue
The house is red and
sometimes blue
The house is red and
sometimes blue
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AP Biology
updated Jan. 2010
Cellular Respiration Lab
For DISCUSSION (may be done on separate paper)
1. VOCABULARY- define the following:
Adenosine diphosphate (ADP)
Adenosine triphosphate (ATP)
Carbon dioxide (CO2)
Cellular respiration
Germination
Dormancy
2. In this investigation, you are investigating both the effect of germination
versus nongermination and warm temperature versus cold temperature on
respiration rate. From the data collected (tables and graph), can you accept or
reject your hypotheses? Why/why not?
3. This activity uses a number of controls. Identify at least three of the controls,
and describe the purpose of each control.
4. Analyze the graphed results for respiration of the peas at both room
temperature and 10 0C.
a. What is the independent variable?
b. What is the dependent variable?
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AP Biology
updated Jan. 2010
Cellular Respiration Lab
5. Describe your graph, in as much detail as possible.
6. Table 5.2 shows CO2 production of germinating and dry peas during the
experiments at room temperature and 100C. Looking at this, and the slope of the
line of Graph 5.1, during which time interval was gas production the greatest?
The least? How might different variables affect this?
7. Describe and explain the relationship between the amount of CO2 produced and
time.
8. Summarize the effect of germination (versus nongermination) on peas seed
respiration.
9. Why did the respirometer have to be completely sealed around the stopper?
What are some possible errors that could take place in this experiment?
10. If you used the same experimental design to compare the rates of respiration
of a 25g. reptile and a 25g. mammal, at 100C, what results would you expect/
Explain your reasoning.
11. If respiration in a small mammal were studied at both room temperature (210C)
and 100C, what results would you predict? Explain your reasoning.
12. Read through Lab 5 in the AP Student Laboratory Manual. (a) Note at least
three differences between that lab setup and the way that we did our lab. (b) Did
we achieve the same objectives, using different methods? Explain.
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