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Name _________________ Period # _______ Respiration Lab Date ______________ Biology In Class Pre-Cellular Respiration Activity 1. Why do we need to breathe (don’t answer: “to live”)? 2. What makes us breathe harder? 3. When we are running around or playing really hard we sometimes need to stop and we feel “out of breath”. What does this feel like? 4. Why do you think this happens? 1 Name _________________ Period # _______ Respiration Lab Date ______________ Biology BREATH OF LIFE- UNLOCKING THE SUGAR INSIDE OF YOU TO MAKE ATP Measuring the Differences in Carbon Dioxide Production With Varying Activities Background Each cell of your body, including your muscle cells, gets ATP energy from sugar by combining the sugar with oxygen (which you breathe in). The result of this chemical reaction is carbon dioxide and water. Your body uses some of the water and exhales the carbon dioxide. This process is called cellular respiration. The process takes 3 steps: glycolysis, Krebs Cycle, and Electron Transport Chain. Krebs Cycle and Electron Transport Chain together are referred to as aerobic respirations because both require O2 to occur and both produce CO2. Aerobic respiration produces 36 ATP. Glycolysis is referred to as anaerobic respiration because it does not require O2 and does not produce CO2. Glycolysis produces 2 ATP. Exercise can affect which steps of cellular respiration take place and therefore vary the amount of CO2 produced. Short bursts of activity that require a lot of energy in short amounts of time (01.5 minutes) such as maximum weight lifting and sprinting will use glycolysis and no aerobic respiration because you are unable to obtain enough O2 to supply the muscles. In order to have enough ATP to meet the high energy demands, lactic acid fermentation will occur to successfully continue glycolysis during the activity. However, during sustained, low energy activities like endurance training (jogging) the muscles have time and need to produce large amounts of ATP through aerobic respiration. Bromothymol Blue Indicator Reaction to Measure CO2 When carbon dioxide enters water it makes the water more acidic. Bromothymol blue is a chemical that changes color (blue to green) if exposed to acid. In other words, Bromothymol Blue will change colors (blue to green) when CO2 is present. Using the Titration Technique described below, you can compare the amount of carbon dioxide produced by people at different levels of activity. The Titration Technique: Procedure: Use a straw to exhale air into a flask containing a solution of bromothymol blue. When the solution changes colors, practice changing it back again by adding drops of sodium hydroxide. The more drops of sodium hydroxide needed, the greater the amount of carbon dioxide in the flask. Practice this procedure until you are comfortable with adding the sodium hydroxide. (Important, you need to swirl the flask after adding the drops to see if the color changes, sometimes the change is delayed) 2 Name _________________ Period # _______ Respiration Lab Date ______________ Pre- Lab: Read the lab and answer the following questions. Biology 1. What is the purpose (main goal) of cellular respiration? 2. Under what conditions does cellular respiration best achieve its goal? Explain. 3. What does the amount of carbon dioxide a person exhales tell you about the rate of aerobic respiration? 4. Explain how Bromothymol Blue and sodium hydroxide can determine how much CO2 you produce. 5. What is the control in this study? 6. Which person in the experiment 1 or 2 is likely to use aerobic respiration for his/ her activity and which is likely to use anaerobic respiration (glycolysis). Justify your answer. 7. Which person do you expect to produce more CO2 person 1 or person 2? Using your knowledge about cellular respiration and the background information above, explain your prediction with a rationale for why you think that. 8. Write a hypothesis for this experiment addressing which person is more likely to perform aerobic respiration and produce more CO2. 3 Name _________________ Period # _______ Respiration Lab Practice Experiment Date ______________ Biology 1. Pour 25 mL of Bromothymol Blue solution into a 50 mL beaker. 2. Using a straw, gently blow into the solution until the color changes from blue to green. 3. Using the provided sodium hydroxide (NaOH), use the titration method described above to determine the amount of CO2 is present. Record that number in chart below. That was practice. Repeat these steps only if you had trouble titrating the first time. Experiment 1. Select 2 people in group to be test subjects and assign one person as #1 and the other as #2. 2. Measure the respiration (breathing) rates (RR) of each person by counting how many breaths they take normally over 15 seconds and multiplying by 4 for one minute. Record in table. 3. Pour 100 mL of Bromothymol Blue solution into flask 1 and another 100mL of Bromothymol Blue solution into flask 2. 4. Using a clean straw, person #1 should be fully rested and blow through his straw into flask #1 and person #2 should do the same into flask #2. 5. Using the NaOH, titrate both solutions to determine the amount of CO2 present. 6. Person #1 will perform the following activity for 10 seconds: sprinting full speed. 7. At the completion of 10 seconds, person #1 will immediately blow into the flask 1 Bromothymol Blue solution with the same straw until the solution turns green. 8. Also immediately following the exercise, you should get the respiration rate of person #1. Record in table. 9. Titrate the green solution NaOH until it turns blue and record in table. 10. Person #2 will perform the following activity for 5 minutes: steady jogging. 11. At the completion of 5 minutes, person #2 will immediately blow into the flask 2 Bromothymol Blue solution with the same straw until the solution turns green. 12. Again, also get the respiration rate of person #2 immediately after exercise and record. 13. Titrate the green solution NaOH until it turns blue and record in table. 14. Clean up the flasks and beakers, throw out the straws, and return all equipment to your station dry. 15. Answer the post-lab questions. 4 Name _________________ Period # _______ Respiration Lab Date ______________ Biology Data Practice Titration Amount of NaOH: ____________drops NaOH Person # Name Activity Done & Time Resting RR Per Minute Exercise RR Per Minute # Drops NaOH at rest # Drops NaOH after activity 1 2 Lab Questions 1. Who produced the most CO2 as evidenced by #drops of NaOH and explain why you think you got this result. 2. How did exercise affect the amount of CO2 produced? 3. Was your hypothesis correct or not? If correct, explain your rationale behind making your hypothesis that was proven true or if incorrect state what you have learned from this experiment that proves your hypothesis wrong. 4. Although we are measuring CO2, what 2 processes are we really trying to isolate and test? What conditions are necessary for each process to occur? 5. Which exercise corresponded to each process identified in question #4 and explain how you knew using the data you obtained. 6. Which person #1 or #2 was breathing heavier after exercise? Why do you think this was the case? (use p. 230-231 to help you). 7. What is the purpose of cellular respiration? Write the equation after stating the main goal. 5 Name _________________ Period # _______ Respiration Lab Application Questions Date ______________ Biology 8. Certain types of bacteria thrive in conditions that lack oxygen. What does that fact indicate about the way they obtain energy? Which person #1 or #2 in the lab functioned in a similar way to the bacteria? 9. In certain cases, regular exercise causes in increase in the number of mitochondria in muscle cells. Which type of exercise, steady low intensity or fast high intensity exercise, would be most likely to yield this result? Explain your answer being sure to include how the increase in mitochondria might improve the individual’s ability to perform energy- requiring activities. 10. Would individuals who carry out steady low intensity exercise suffer more or less muscle discomfort during and after exercise than an individual performing fast high intensity exercise? Explain your answer. 11. Knowing that the heart is made of muscle, after a heart attack, small amounts of lactic acid are present in the blood. What does this evidence suggest about the nature of a heart attack? 6