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AP Biology Lab 5
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AP Biology Lab 5: Cell Respiration
Driving Questions
In this lab you will compare the respiration rates in dormant and germinating seeds.
Do both germinating and non-germinating beans undergo cellular respiration?
What is the effect of temperature on respiration rates in beans?
If Crickets are used… What is the effect of temperature on respiration rates in crickets.
Background
The term respiration refers to the exchange of gases between and organism and its environment. This intake of oxygen gas and exhalation of carbon dioxide gas is closely linked to the production of ATP at the cellular level, a process called cellular respiration. ATP is generated by mitochondria within the cell. During cellular respiration, the energy stored within macromolecules such as glucose is released and harnessed to phosphorylate ADP, producing ATP. In the presence of oxygen, glucose can be fully oxidized releasing large amounts of energy.
C6H12O6 + 6 O2 (g) → 6 H2 + 6 O CO2 ( ) + g energy
The process of cellular respiration also produces water and carbon dioxide gas as waste products.
Organisms that utilize oxygen for the breakdown of glucose are called aerobic organisms. Plants and animals are both examples of aerobic organisms. One big question is, if plants can convert solar (light) energy into carbohydrate, then why do they need to do cellular respiration? Further, do plant embryos (seeds) go through cellular respiration, and is cellular respiration dependent on environmental factors? In this lab, you will determine if there is a difference in respiration rates of dormant and germinating pea seeds. You will also determine the effect of temperature on respiration rates of both types of peas. During our next session, you will set up original experiments to test the effects of environmental changes on cricket respiration.
Materials and Equipment
Electronic data collection and display device Ice
1 carbon dioxide gas sensor
3 plastic bottles
25-50 germinating pea seeds
25-50 dry pea seeds
1 temperature probe Glass beads
1 10 C water bath & 1 21 C water bath Crickets (if instructors provides them)
Lab Safety
Emphasize the need to keep water away from any non-waterproof electronics.
Keep water away from electrical outlets.
Sequencing Challenge
The steps below are part of the Procedure for this lab activity. They are not in the right order. Determine the
proper order and write numbers in the circles that put the steps in the correct sequence.
Procedure - Carbon Dioxide Gas Produced By Alaska Peas
After you complete a step (or answer a question), place a check mark in the box () next to that step.
Set Up Equipment & Collect Data
1. Connect the CO2 sensor and the temperature probe to the electronic data collection and display device.
2. Place 25-50 germinating peas into one of plastic bottles and insert a calibrated CO2 sensor into the top of the bottle. Be sure that the bottle is tightly sealed by firmly pressing on the rubber stopper connected to the sensor. Place the experimental chamber in a room temperature cooler (or leave out on the lab bench top).
4. Begin collecting data. Set your SPARK or GLX to collect data every five seconds. After five minutes, stop data collection.
5. Select Statistics Tool to determine the maximum and minimum CO2 concentration in the respiration chamber as well as the overall rate of respiration (ppm/min) record your results in Table 5.2. (Ask Ms. Stone for help with this.)
6. Remove CO2 sensor and empty the germinating beans into a small container of 10-15 C water.
7. Place 50 dry mung beans into the plastic bottle and insert the CO2 sensor into the top of the bottle.
8. Repeat steps 3-6 for the dry beans.
9. What is the purpose of testing CO2 production in dry seeds?
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Determine the amount of carbon dioxide produced by dry peas at room temp.
Determine the amount of carbon dioxide produced by germinating peas at 10 C.
Determine the amount of carbon dioxide produced by germinating peas at room temperature.
Determine the amount of carbon dioxide produced by germinating peas that have been boiled (or incubated at some other temperature.
10. Obtain the plastic bottle containing the 50 germinating beans that have been incubating in on ice water bath, blot dry and place into the plastic bottle. Re-insert the CO2 gas sensor into the bottle.
11. Repeat steps 3-5 to determine respiration rates at of germinating peas at 10C.
12. After completing step 11, run a similar experiment for germinating peas at a temperature besides 10C (on ice) or room temperature.
Data Analysis
16. Determine the rate of CO2 production by the beans and crickets in each run. Record all appropriate data in table 5.2 (below)
Table 5.2: Rates of cellular respiration for test subjects at varying temperatures.
Run #
Set-UpAvg. TempDuring run
Minimum [CO2] ppm
Maximum [CO2] ppm
Respiration Rate ppm/sec
1 Dry Peas
2Germinating Peas (room temp)
3Germinating Peas (chilled)
4Germinating Peas (alternate temp)
17. Using a graphing template (See last page), prepare a graph of respiration rates for all peas in all runs. Be sure label your axes with units, and set an appropriate scale. Include a legend with your graph indicating the test subjects and the temperatures of each run.
Cellular Respiration Analysis Questions
1. Does germination affect the rate of seed (= bean) respiration? Use evidence from your experiments to support your claim. If there is a difference in cellular respiration between germinating and dormant beans, explain why. Be as specific as possible in your explanation.
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2. Does temperature affect the rate of cellular respiration in crickets? Further, does temperature affect the rate of cellular respiration in crickets? If so, what evidence do you have to support your claims? ______________________________________
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3. Explain differences in the respiration rates of room temperature and refrigerator temperature crickets. Make sure to include the role of enzymes in these metabolic pathways as well as transport across cell membranes in your answer.
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4. Explain why carbon dioxide production is a valid way to determine rates of cellular respiration. ___________________________________________________________________________________________
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5. Why did we use CO2 production instead of oxygen consumption as a metric of cellular respiration?
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Synthesis Questions
Use available resources to help you answer the following questions.
1. _Imagine that we conducted the room temperature experiment with the same numbers of different beans (Alaska peas, chick peas, lima beans). Would you anticipate that all seeds would show similar rates of cellular respiration? Why or why not________________________________________________________________________________
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2. If you used a similar experimental design to test the effects of 10 C on a 25-g mammal, and a 25-g reptile what results would you expect? Explain your reasoning. ___________
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3. Now, take the same small mammal you stuffed in the experimental chamber during synthesis question 2 and subject the little varmint to a temperature change of 21C to 4 C. What would happen to the CO2 concentration in the experimental chamber? Explain your reasoning.
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4. In the space below graph the rates of cellular respiration of beans that began germinating at the following points in the past (12 hours ago, 24 hours ago, 48 hours ago, and 72 yours ago). Offer a brief explanation for your predicted results.
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AP Biology Graphing TemplateFall 2010AP lab 5
Title:_______________________________________________________________________
