Biology Unit 2, Structure of Life, Lab Activity 2-3

Transcription

1 Biology Unit 2, Structure of Life, Lab Activity 2-3 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. A mole is a measure of the number of molecules. The energy released is captured by organisms as ATP or released as heat. C6H12O6 + 6 O2 6 CO2 + 6 H2O kilocalories of energy/mole of glucose oxidized By studying the equation above, you will notice there are three ways cellular respiration could be measured. You could measure the: 1. Consumption of O2. (How many moles of O2 are consumed in cellular respiration?) 2. Production of CO2. (How many moles of CO2, are produced in cellular respiration?) 3. Release of energy during cellular respiration. In this experiment, the relative volume of 02 consumed (option #1) and the production of CO2 (option #2) by germinating and non-germinating (dry) peas at two different temperatures will be measured. The rate of plant respiration will then be compared to the rate of respiration in an animal. Research Question What factors control the rate of cellular respiration in plants and animals? Write your answer to the research question AFTER completing all parts of the lab. PROTOCOL MATERIALS Computer 250 ml respiration chamber Computer interface Logger Pro software ice cubes thermometer O2 and CO2 Gas Sensor two beakers 25 germinating peas 10 live crickets 25 non-germinating peas

2 Procedure Data collection for this lab is to be completed as a lab table group. Data reporting and questions are to be completed individually. Part I Germinating and non-germinating peas, room temperatures 1. Connect the CO2 Gas Sensor to Channel 1 and the O2 Gas Sensor to Channel 2 of the Vernier computer interface. 2. Prepare the computer for data collection by opening the file 11D Cell Respiration (CO2 and O2) from the Biology with Computers folder of Logger Pro. 3. Obtain 25 germinating peas and blot them dry between two pieces of paper towel. Measure the room temperature. Record the temperature in Table Place the germinating peas into the respiration chamber. 5. Place the O2 Gas Sensor into the rubber gasket on the side of the respiration chamber. Insert the sensor snugly. The O2 Gas Sensor should remain vertical (this side up) throughout the experiment. Place the CO2 Gas Sensor into the top of the respiration chamber. The CO2 Gas Sensor will not be damaged if it remains horizontal. Do not twist the shaft of the CO2 Gas Sensor or you may damage it. Calibrate the O2 sensor if readings are not close to 210 ppt O2 for room oxygen content. Calibrate the CO2 sensor if readings are much below ppt. (your teacher will show you how). Answer Stop question #1 before collecting data 6. Wait one minute for readings to stabilize, then begin collecting data by clicking. Collect data for ten minutes and click. 7. When data collection has finished, remove the both sensors from the respiration chamber. Place the peas in a 250 ml beaker filled with cold water and ice. 8. Fill the respiration chamber with water and then empty it. Thoroughly dry the inside of the respiration chamber with a paper towel. 9. Determine the rate of respiration: a. Click anywhere on the CO2 graph to select it. Click the Linear Fit button to perform a linear regression. A floating box will appear with the formula for a best fit line. b. Record the slope of the line, m, as the rate of respiration for germinating peas at room temperature in Table 2. c. Close the linear regression floating box. d. Repeat Steps 9a c for the O2 graph. 10. Move your data to a stored run. To do this, choose Store Latest Run from the Experiment menu. 11. Obtain 25 non-germinating peas and place them in the respiration chamber Answer Stop question #2 before continuing 12. Repeat Steps 5 10 for the non-germinating peas. Portions adapted from Advanced Biology with Vernier by permission Page 2 of 7

3 Part II Germinating peas, cool temperatures 13. Remove the peas from the cold water and blot them dry between two paper towels. Answer Stop question #3 before collecting data 14. Repeat Steps 5 9 to collect data with the germinating peas at a cold temperature. 15. To print a graph of concentration vs. volume showing all three data runs: a. Click anywhere on the CO2 graph. Label all three curves by choosing Text Annotation from the Insert menu, and typing Room Temp Germinated (or Room Temp Non-germinated, or Cold Germinated ) in the edit box. Then drag each box to a position near its respective curve. Adjust the position of the arrow head. b. Print a copy of the graph for each lab member (select File>Print Graph), with all three data sets and the regression lines displayed. Enter your name(s) and the number of copies of the graph you want. c. Click on the O2 graph and repeat the process to print copies of the O2 graph. Answer Stop question #4 before continuing Part III Animal Respiration 16. Repeat steps 1-10 and using 10 crickets instead of peas. Do not immerse the crickets in cold water, step 7, following data collection (they don't like that). Instead of placing them in cold water put then in the refrigerator for 5 minutes. You will only have two runs (room temperature and cold) for the cricket respiration graphs. 17. Rinse the chambers thoroughly and set them to dry when you are done. Answer Stop question #5 before collecting data Now that you have read these procedures construct a flow chart on the following page. Portions adapted from Advanced Biology with Vernier by permission Page 3 of 7

4 Flow Chart Lab 2-3 Respiration Portions adapted from Advanced Biology with Vernier by permission Page 4 of 7

5 Data DATA Table 1 Condition Temperature ( C) Room Cold water Peas Germinating, room temperature Non-germinating, room temperature Germinating, cool temperature Table 2 CO2 Rate of respiration (ppt/min) O2 Rate of consumption (ppt/min) tape pea respiration graphs (CO2 and O2) here tape cricket respiration graphs (CO2 and O2) here They will overlap like this when you have them taped in Portions adapted from Advanced Biology with Vernier by permission Page 5 of 7

6 Stop Questions 1) Predict what will happen with the dry peas. Will they be using any oxygen or producing any CO2 at all? Explain your reasoning (your explanation is what you will get credit for) 2) Is it important to calibrate the sensors? Would the rate be the same if the sensor read a lower %? Explain your reasoning (your explanation is what you will get credit for) 3) Predict what will happen with the cold peas. Will the respiration rate be higher or lower? Explain your reasoning (your explanation is what you will get credit for) 4) Did the results you collected agree with your predictions? Support your answer with specific data from the experiment. 5) Predict what will happen with the crickets. Will there rate of respiration be higher or lower than the germinating peas? Explain your reasoning (your explanation is what you will get credit for) Analysis Questions 1. The peas are green. They are plants. Do you think they are also producing oxygen? Explain your reasoning (your explanation is what you will get credit for) 2. What part of the plant and animal cells is using the oxygen? 3. Is the oxygen really gone from the chambers? If Yes, where did it go? If No, where is it? 4. Why do the peas use oxygen? 5. Why do the crickets use oxygen? 6. In the chambers the oxygen level drops. In our atmosphere it stays pretty constant at around 21%. What process replenishes the oxygen in our atmosphere that all of the plants and animals use? Conclusion Design an experiment that would compare the respiratory rate of a 25 gram reptile and a 25 gram mammal at 10 C. Include a graph of your expected results and explain why you would expect the results you presented. Your graph will have two lines, one for the reptile and one for the mammal. Experimental Design Manipulated Variable Responding Variable Constants,, Experimental setup Portions adapted from Advanced Biology with Vernier by permission Page 6 of 7

7 Oxygen gas O2 (%) Carbon Dioxide gas CO2 (ppm) Predicted Graph of Results for Conclusion Explanation (not a description) of graphed results Portions adapted from Advanced Biology with Vernier by permission Page 7 of 7