AP Lab 5 Cell Respiration Name: __________________ (O2 Gas Sensor) Background Cell respiration refers to the process of converting the chemical energy of organic molecules into a form immediately usable by organisms. Glucose may be oxidized completely if sufficient oxygen is available according to the following equation: C6H12O6 + 6O2 > 6 H2O + 6 CO2 + energy (686 kcal/mole) All organisms, including plants and animals, oxidize glucose for energy. Often, this energy is used to convert ADP and phosphate into ATP. Peas undergo cell respiration during germination. Do peas undergo cell respiration before germination? Additionally, as we have learned before, temperature can also affect biological processes and the rates at which they occur. Using your collected data, you will be able to answer two questions at the completion of this lab:

• Do non-germinating (dormant) peas respire? If so, at what rate? • Does temperature affect the respiration rate of germinating peas?

By studying the equation for cellular respiration shown above, you should notice that there are 3 ways that cellular respiration could be measured. One could measure the:

• Consumption of O2 (how many moles of oxygen are consumed in cellular respiration?) • Production of CO2 (how many moles of carbon dioxide are produced in cellular respiration?) • Release of energy during cellular respiration

OBJECTIVES In this experiment, you will:

• Measure oxygen gas. • Study the effect of temperature on cell respiration. • Determine whether germinating peas and non-germinating peas respire. • Compare the rates of cell respiration in germinating and non-germinating peas.

MATERIALS

• 25 germinating peas • 25 non-germinating peas • Vernier computer interface • 250 mL respiration chamber • Vernier O2 Gas Sensor • ice cubes • two 100 mL beakers • thermometer

PROCEDURE Part I: Respiration in germinating peas vs. non-germinating peas 1. Connect the O2 Gas Sensor to the computer interface. 2. Obtain 25 germinating peas and blot them dry between two pieces of paper towel. Use the thermometer to measure the room temperature. Record the temperature in Table 1. 3. Place the germinating peas into the respiration chamber. 4. Place the O2 Gas Sensor into the bottle as shown in Figure 1. Gently push the sensor down into the bottle until it stops. The sensor is designed to seal the bottle without the need for unnecessary force.

Figure 1 5. Wait two minutes, then begin collecting data. Record the readings for oxygen gas in your data table every minute for 10 minutes. 6. When data collection has finished, remove the O2 Gas Sensor from the respiration chamber. Place the peas in a 100 mL beaker filled with cold water and an ice cube. 7. Fill the respiration chamber with water and then empty it. Thoroughly dry the inside of the respiration chamber with a paper towel. 8. Obtain 25 non-germinating peas and place them in the respiration chamber 9. Repeat Steps 4–7 for the non-germinating peas. Part II: Respiration of germinating peas in different temperatures 10. Remove the germinating peas from the cold water and blot them dry between two paper towels. 11. Repeat Steps 3–7 to collect data with the germinating peas at a cold temperature.

ANALYSIS 1. Make a graph showing the results of the experiment. All data collected should be displayed on one graph. Be sure to clearly label both axes (don't forget units), used different colors and give a key as needed, use appropriate scaling on both axes, and provide an appropriate title. "Cell Respiration Lab" is NOT an appropriate title. CONCLUSION 2. Describe the relationship between the amount of oxygen consumed and time. 3. What is the effect of germination on the rate of cell respiration in peas? Explain. 4. What is the effect of temperature on the rate of cell respiration in peas? Explain. 5. Why do germinating peas undergo cell respiration? 6. If you used the same experimental design to compare the rates of respiration of a 25g reptile and a 25g mammal at 10 deg. Celcius (chilly), what results would you expect? Explain your reasoning. 7. If respiration of a mammal were studied at both room temperature (21 deg. C) and chilled (10 deg. C) what results would you expect? Explain your reasoning. 8. Why did you have to use 25 peas?

EXTENSIONS: Design an experiment for each of the following investigations: 1. Compare the respiration rate among various types of seeds. What types of seeds would you use? How many of each? What is your IV? What is your DV? Would you have a control treatment? If so, what? What should you hold constant? Describe your procedure: Create a data table for the experiment. Make a hypothesis about your results:

2. Compare the respiration rate among seeds that have germinated for different time periods. What type of seeds would you use? How many in each treatment? What different time periods of germination would you compare? What is your IV? What is your DV? Would you have a control treatment? If so, what? What should you hold constant? Describe your procedure: Create a data table for the experiment. Make a hypothesis about your results:

3. Compare the respiration rate among various types of small animals, such as insects or earthworms. What type of animals would you use? How many of each? What is your IV? What is your DV? Would you have a control treatment? If so, what? What should you hold constant? Describe your procedure: Create a data table for the experiment. Make a hypothesis about your results: