AP Biology Learning Objectives Investigation 6: Cellular Respiration To learn how a respirometer system can be used to measure respiration rates in plant seeds or small invertebrates, such as insects or earthworms. To design and conduct an experiment to explore the effect of certain factors, including environmental variables, on the rate of cellular respiration. To connect and apply concepts, including the relationship between cell structure and function (mitochondria); strategies for capture, storage, and use of free energy; diffusion of gases across cell membranes; and the physical laws pertaining to the properties and behaviors of gases. Pearson Education, Inc., publishing as Person Benjamin Cummings College Board, AP Biology Curriculum Framework 2012-2013 Copyright Rebecca Rehder Wingerden Background Living systems require free energy and matter to maintain order, to grow, and to reproduce. Organisms employ various strategies that have been conserved through evolution to capture, use, and store free energy. - Autotrophic organisms capture free energy from the environment through photosynthesis and chemosynthesis. - Heterotrophic organisms harvest free energy from carbon compounds produced by other organisms. Background The process of cellular respiration harvests the energy in carbon compounds to produce ATP that powers most of the vital cellular processes. In eukaryotes, respiration occurs in the mitochondria with in cells. The chemical oxidation of glucose can be summarized by the following reaction: C6H12O6 + 6(g) 6(g) + 6H2O + energy What could you measure to determine the overall rate of cellular respiration?
Respirometer is a device used to measure the rate of exchange of and/or. In a respirometer the gas molecules are sealed by the liquid manometer fluid plug. Gaseous is absorbed and combined with the KOH to form a solid compound removing molecules from the interior atmosphere of the respirometer. As is consumed by cellular respiration the overall gas volume inside the respirometer decreases. The air pressure outside the respirometer is greater which forces the manometer fluid plug into the capillary tube. Respiration can then be measured by the movement of the manometer fluid plug along the small capillary tube. Bozeman Biology: AP Biology Lab 5 Cellular Respiration (6:00 min.) http://www.bozemanscience.com/ap-bio-lab-5-cellular-respiration Bozeman Biology: Cellular Respiration Lab Walkthrough (10:00 min.) http://www.bozemanscience.com/cellular-respiration-lab-walkthrough PreLab Complete the following before conducting this investigation: I. Read. II. Answer the following PreLab questions in Comp Book: 1. Summarize what you will be doing in this investigation. 2. What is the primary question you will be trying to answer in this investigation? Experiment Set Up: III. Getting Started: 1. Complete Inv. 6 Cellular Respiration: Getting Started: Questions 1-6 (p.s73) Hint: Several tutorials and animations explaining the general gas law are available online (e.g., http:// www.nclark.net/gaslaws). Germinating (20) NonGerminating (20) Oxygen gas sensor Carbon Dioxide gas sensor LabQuest2
Procedure: Baseline Using the Gas Sensor and Gas Sensor, you will monitor the carbon dioxide produced and the oxygen consumed by peas during cell respiration. 1. Start up LabQuest2 and connect Gas Sensor and Gas Sensor. 2. Place 20 germinating seeds into the BioChamber250. 3. Insert Gas Sensor and Gas Sensor to the BioChamber250 (see fig. 1). 4. Wait 5 minutes for Gas Sensor etc warm up and readings to stabilize, then begin collecting data by tapping Collect. 5. Collect data for 5 minutes. To stop data collection click Stop. Sensor needs to warm up for 5 minutes. fig. 1 Check Mode: Time Based Rate: samples/s Duration: 300 sec. (5 min). 6. When data collection has finished, remove the sensors from the respiration chamber, remove seeds, and fill the respiration chamber with water and then empty it. Thoroughly dry the inside of the respiration chamber prior to reuse. Procedure: Baseline (cont.) 7. To determine the rate of respiration: a. Click Analyze, Curve Fit, select data, choose Linear, then OK. b. Record the slope of the line, m, as the rate of respiration for germinating seeds at room temperature in Table 1. c. Repeat Steps 7a-b for the graph. 8. Repeat Steps 3-7 with nongerminated seeds and record in Table 2. Share data with class (Table 1 and Table 2). When your system is ready to begin collecting data, tap on green arrow. Data: Baseline Table 1: Rate of Respiration In Germinating Seeds (baseline) period Group (room ºC) Number Seeds 1 2 3 4 5 6 7 8 Average Rate of Respiration Rate of consumption
Data: Baseline Table 2: Rate of Respiration In Non-Germinating Seeds (baseline) period Group 1 2 3 4 5 6 7 8 (room ºC) Number Seeds Average Rate of Respiration Rate of consumption Conduct Baseline: Procedure Completed Share and Copy Data: Table 1 and Table 2 Analysis: Baseline Assessment- Baseline: questions 1-5 (Handout) Designing and Conducting Your Investigation: Determine a questions about Cellular Respiration that your group would like to investigate. Before you start designing your experiment, your question must be presented, discussed, and approved by instructor. Designing Your Investigation: Purpose: method that will be used, independent and dependent variable. Hypothesis: If (rational for the investigation), then (outcome that you would expect). Procedure: Steps discussing how you will modify the baseline procedure: independent (levels), dependent, control and standardized variables. Data: table(s) to record findings (Three Trials). Approval by Instructor Conduct Your Investigation: Procedure: Conduct your Experimental Design Data Collection: Table(s) Complete Analysis: Experiment Assessment- Experimental: questions 1-4 (Handout) Table 4: Average Rate of Respiration In Experimental Data (Class) Graph 1: Average Rate of Respiration In Experimental Data (Class)
Table 4: Average Rate of Respiration In Experimental Data (Class) period Graph 1: Average Rate of Respiration In Experimental Data (Class) Variable (ºC) Average Rate of Respiration Average Rate of consumption Average Average Non- (30ºC) (10ºC) Mung Mung (36ºC) Red Corn Tropical Plant leaf Crickets Variable Whiteboard Presentation: Purpose: method that will be used, independent and dependent variable. Hypothesis: If (rational for the investigation), then (outcome that you would expect) because Procedure: Steps discussing how you modified the baseline procedure: independent (levels), dependent, control and standardized variables. Bar Graph: Rate (Baseline -vs- Experimental). Summary Statement: Describe how the IV influences the DV. (Claim - Evidence - Reasoning) What was the effect of the variable your group investigated on the rate of cellular respiration?