Aerobic & Anaerobic Conditions HASPI Medical Biology Lab 11 Background/Introduction The Flow of Energy & Cycling of Matter Photosynthesis and cellular respiration (including aerobic and anaerobic respiration) provide most of the energy for life processes. Energy drives the cycling of matter within and between systems. Producers are capable of obtaining energy through photosynthesis and matter from the atmosphere, water, or soil. Consumers obtain their energy from consuming producers or other consumers, and can also obtain matter from the atmosphere, water, or soil. Consumers also obtain matter from the organisms they consume. CO2 + H2O Pyruvate! Any atom, molecule, or ion required for an organism to grow, survive, and reproduce is considered a nutrient. For example, carbon, hydrogen, oxygen, and nitrogen are important atoms required for life. Organisms consume these atoms in the form of molecules such as water (H2O), oxygen (O2), and glucose (C6H12O6). The molecules are broken down and used by organisms, or eliminated as waste. Since matter cannot be created or destroyed, it is important that these atoms and molecules are cycled. The matter in waste or decomposing organisms is returned to the atmosphere, water, or soil where it can be reused by producers and/or consumers and re-enter the cycle. Living things are dependent on the ability of nutrients (matter) to cycle, and nutrients do not cycle without energy. The cycling of matter is dependent on the flow of energy. Aerobic and Anaerobic Conditions Through photosynthesis and cellular respiration, producers and consumers can obtain the energy required to cycle matter. Producers use photosynthesis to convert solar energy into chemical energy and glucose. Producers require most of this energy, but consumers can obtain some of the energy when they consume producers. Consumers also obtain glucose, which can be broken down during cellular respiration to produce additional energy. It is important to note that producers AND consumers can perform cellular respiration, but ONLY producers can perform photosynthesis. When organisms have oxygen available, they can perform a type of cellular respiration called aerobic respiration. Aerobic respiration uses oxygen and glucose to produce large amounts of chemical energy, or adenosine triphosphate (ATP). ATP can be used or stored by the cells of the body for energy. Large active consumers need aerobic respiration to produce enough energy to survive. The chemical equation for aerobic respiration is: glucose(c6h12o6) + oxygen(o2) à carbon dioxide(co2) + water(h2o) + 38 ATP Sunlight (solar energy) Cellular Respiration (mitochondria) 36 ATP Photosynthesis (chloroplast) Glucose Glycolysis (cytoplasm) Aerobic & Anaerobic Conditions, HASPI Medical Biology Lab 11 311 O2 O2 2 ATP
If oxygen is not available, organisms can perform a type of cellular respiration called anaerobic respiration, or fermentation. Anaerobic respiration can use glucose to produce small amounts of chemical energy. Large consumers can only survive on the energy produced from anaerobic respiration for a short amount of time due to their large energy demands. Prolonged use of anaerobic respiration for energy will eventually lead to muscle fatigue. Smaller consumers and producers can survive longer on the energy produced through fermentation. There are two types of fermentation: Lactic Acid Fermentation used by muscle cells and bacteria. Produces lactic acid as a by-product. The chemical equation for lactic acid fermentation is: glucose(c6h12o6) à lactic acid(c3h6o3) + 2 ATP Alcoholic Fermentation used by yeast, and can be used to make bread, beer, wine, and other food sources. The chemical equation for alcoholic fermentation is: glucose(c6h12o6) à alcohol(c2h5oh) + carbon dioxide(co2) + 2 ATP Energy, Matter, and Life The food that we eat contains both energy and matter (nutrients). Since we need to consume food to obtain energy and matter, we are considered consumers. Humans and other consumers digest food into simpler substances. Once these substances have been digested, they can be rearranged into other substances that can be used by the body. In this way, matter is not created or destroyed, but instead it is transformed. For example, when we consume a protein source, such as chicken, it is broken down into simpler molecules called amino acids. These amino acids are then rearranged into proteins, such as enzymes, that are needed for the human body to grow and function. Carbohydrates, or sugars, in the food that we eat are energy-rich, and our bodies can create large amounts of ATP when the bonds holding carbohydrates together are split during cellular respiration. Some of this energy is stored or used for body functions, but some of the energy is released as heat. The proof of this can be felt in our steady 98.6 F body temperature. Without this heat release, our body temperature would be the same as our surrounding environment. Review Questions answer questions on a separate sheet of paper http://blog.luckyvitamin.com/wpcontent/uploads/2009/08/energy_and_life2.jpg 1. Which processes provide most of the energy for life? 2. How are energy and matter related? Explain your answer. 3. What is the difference between a producer and a consumer? 4. What is a nutrient? Where do organisms get nutrients? 5. What is aerobic respiration? What is the chemical equation for aerobic respiration? 6. What is anaerobic respiration (fermentation)? What are the two types of fermentation called? 7. What is the chemical equation for lactic acid fermentation? Alcoholic fermentation? 8. Compare the amounts of energy (ATP) produced in aerobic and anaerobic respiration. Which process is more efficient at producing energy? Explain your answer. 9. Explain how the food we eat provides both energy and matter for our bodies? Give two examples of how our bodies use energy and matter. 312 Aerobic & Anaerobic Conditions, HASPI Medical Biology Lab 11
HASPI Medical Biology Lab 11a Scenario Aerobic and anaerobic respiration are important processes for obtaining energy. Aerobic respiration requires oxygen and produces large amounts of energy, or ATP. Anaerobic respiration occurs without the presence of oxygen and produces less ATP. Due to the fact that aerobic respiration is more efficient, it is our body s primary method of obtaining energy. In fact, at rest our body relies 100% on aerobic respiration for energy. Anaerobic respiration only occurs when there is an oxygen deficit. This can happen during exercise when energy, and therefore oxygen, demands are high. Unfortunately, lactic acid is produced as a byproduct of anaerobic respiration, and its build-up can lead to muscle soreness. In this lab, you will have the opportunity to investigate and observe how the body produces energy in aerobic and anaerobic conditions. Materials Clothespin Thermometer Timer Step or stable chair Thermometer cover Procedure/Directions Your lab team will be given tasks, or directions, to perform on the left. Record your questions, observations, or required response to each task on the right. Part A. Aerobic Conditions in the Body Task Response 1 2 3 The 3-minute step test is commonly used by physicians to measure an individual s aerobic fitness level. In this activity, you will use the 3-minute step test to observe what happens to the body when we increase the demand for energy, and therefore the demand for aerobic respiration. Aerobic respiration requires glucose (C6H12O6) and oxygen (O2) to produce energy (ATP), carbon dioxide (CO2), and water (H2O). When we exercise, we need additional energy. This means our body needs to bring in more oxygen and glucose, and will produce more water and carbon dioxide. Obtain a thermometer, a thermometer cover, a timer, and locate a step or STABLE chair. Choose one member of your group to be the test subject. a. What is the chemical equation for aerobic respiration? b. To what molecule(s) is the carbon in glucose transferred during aerobic respiration? c. To what molecule(s) is the hydrogen in glucose transferred during aerobic respiration? d. What molecule(s) is the oxygen in glucose transferred to during aerobic respiration? e. How is the energy (ATP) produced during aerobic respiration? Aerobic & Anaerobic Conditions, HASPI Medical Biology Lab 11 313
To observe the impact of exercise on the body, you will be measuring the pulse rate, 4 temperature, and respiratory rate of the test subject. In order to have values to compare (control variables), it is necessary to obtain this from the test subject while he/she is resting. Obtaining a Pulse Rate The pulse is actually the arteries expanding with blood in rhythm with the contraction of the heart. Blood carries oxygen from the lungs to the body cells, and carries carbon dioxide from the body cells to be removed by the lungs. The pulse can be taken at a 5 variety of locations on the body. The pulse will increase or decrease based on the amount of oxygen that needs to get to cells in the body, and the amount of carbon 6 dioxide that needs to be removed as a result of aerobic respiration. The most common pulse points are radial, which is on the thumb side of the inner wrist, and carotid, which is on the side of the neck. Take the pulse at one of these sites by counting the number of beats in 15 seconds. Multiply this number by 4 to determine the beats per minute (BPM). f. How can aerobic respiration affect the pulse rate? 7 Record the resting pulse rate in Table 1. Obtaining a Temperature As energy in the body is used to perform daily functions, heat is released from the chemical reaction. This causes the human body to be warmer than the surrounding 8 environment. At rest, the normal human body temperature is 98.6 F, or 37 C. More or less energy used by the body will cause the body temperature to fluctuate slightly. 9 To obtain a temperature, first place the thermometer cover over the end of the thermometer. This allows the thermometer to remain sterile between individuals. Keep the cover on throughout this lab, and discard the thermometer cover once the test subject is done. Turn the thermometer on and place the thermometer in the mouth of the test subject, 10 under the tongue. The thermometer will beep when it has obtained a temperature. 11 Record the resting temperature in Table 1. g. How can aerobic respiration affect the body temperature? Obtaining a Respiration Rate Respiration brings oxygen needed for aerobic respiration into the body, and removes carbon dioxide produced during aerobic respiration. The energy demands on the body 12 can cause the respiration rate to increase or decrease depending on how much oxygen is needed, and how much carbon dioxide needs to be removed. The respiratory rate is the number of breaths an h. How can aerobic respiration affect the individual takes in a minute. To take the respiration rate? respiration rate, simply watch the rise and fall of 13 the test subject s chest. Count the number of breaths for 30 seconds, and multiply this number by 2. 14 Record the resting respiratory rate in Table 1. 314 Aerobic & Anaerobic Conditions, HASPI Medical Biology Lab 11
The 3-Minute Step Test Have the test subject stand facing the step 15 or STABLE chair. When ready, start the timer and have the test subject march up and down quickly on 16 the step/chair for 3 minutes. The stepping rate should be approximately 96 steps per minute. If the test subject needs to rest, he/she can 17 stop for a short period but must remain standing. When 3 minutes are up, immediately have the test subject sit on the step/chair and 18 take the pulse rate, temperature, and respiration rate. Record the new pulse rate, temperature, 19 and respiration rate in Table 1. Did the pulse rate increase Answer: or decrease from the resting rate during the 3-minute 20 step test? In terms of aerobic respiration, explain why this happened. Did the temperature Answer: increase or decrease from the resting temperature 21 during the 3-minute step test? In terms of aerobic respiration, explain why this happened. Did the respiration rate Answer: increase or decrease from the resting rate during the 3-22 minute step test? In terms of aerobic respiration, explain why this happened. Construct an explanation Answer: based on the evidence from this lab for the cycling of matter and flow of energy in aerobic conditions. 23 Table 1. Pulse Rate, Temperature, and Respiration Rate Pulse Rate (beats per minute) Temperature ( C) Respiration Rate (breaths per minute) Resting (Before Exercise) After 3-Minute Step Test Aerobic & Anaerobic Conditions, HASPI Medical Biology Lab 11 315
Part B. Anaerobic Conditions in the Body Task Response When we exercise, our muscles use energy (ATP). Most of this energy is produced from aerobic respiration, but anaerobic respiration can produce energy faster. Anaerobic respiration is most common during high-intensity exercise. It is less efficient, but can 1 provide more energy when muscles need it quickly. The process produces a useless byproduct, lactic acid, which can build up in muscles and is associated with muscle fatigue. When a muscle is unable to contract with the same force, muscle fatigue is occurring. In this part of the activity, you will observe how high-intensity exercise can lead to muscle fatigue, which can be used as a sign that anaerobic respiration has occurred in the body. 2 Obtain a clothespin and a timer. Decide who will be the test subject for this investigation. Table 2. Number of Have the test subject grasp the clothespin Clothespin Squeezes 3 between the thumb and forefinger of the Trial # of Difference dominant hand. # Squeezes from Trial 1 4 When ready, start the timer and say GO! The test subject should start squeezing the 1 N/A clothespin open and closed as fast as possible for 2 5 15 seconds, counting the number of squeezes. 3 At 15 seconds have the test subject stop 4 6 squeezing the clothespin, and QUICKLY record the 5 number of squeezes in Table 2 for Trial 1. 6 7 The test subject should REST ONLY 5 SECONDS! 7 After 5 seconds, have the test subject squeeze the 8 8 clothespin again (same hand) for 15 seconds. 9 Record the number of squeezes in Table 2, Trial 2. 10 Continue with a 15-second test and 5-second rest 11 9 interval for a total of 15 trials. Record the results in 12 Table 2. No switching fingers or hands! 13 When finished, subtract the number of squeezes 14 10 for each trial from trial 1. Record the values in 15 Table 2. How does muscle fatigue Answer: 11 indicate that anaerobic respiration has occurred? What happened to the Answer: number of clothespin 12 squeezes as the number of trials increased? Hypothesize why this happened. Construct an explanation Answer: based on the evidence from 13 this lab for the cycling of matter and flow of energy in anaerobic conditions. 316 Aerobic & Anaerobic Conditions, HASPI Medical Biology Lab 11
HASPI Medical Biology Lab 11b Scenario Fermentation is a form of anaerobic respiration, meaning that it produces energy without oxygen. The fermentation converts sugar into an alcohol or acid, and produces carbon dioxide and a small amount of energy (ATP) in the process. The fermentation process in yeast and humans is similar, but in humans the process produces lactic acid, and in yeast it produces ethanol. The following chemical equation summarizes the fermentation reaction in yeast: 2 CO2 + 2 C2H5OH + 2 ATP C6H12O6 glucose carbon dioxide ethanol energy In this activity, your team will set up a model to observe and predict fermentation in yeast. Materials 2 Whirl-pak bags 1000 ml Beaker Timer Yeast (10 g) Graduated cylinder Balance scale Sugar (5 g) Heat source Soda/juice Water Paper towels Thermometer Procedure/Directions Your lab team will be given tasks, or directions, to perform on the left. Record your questions, observations, or required response to each task on the right. Part A. Observing Fermentation Task Response 1 Obtain two whirl-pak bags, a 1000 ml a. What is fermentation? Is it aerobic or anaerobic? beaker, and a graduated cylinder. 2 Use the balance scale and a weighing boat to weigh out 5 g of yeast. Pour the yeast into the whirl-pak bag. Yeast is a living organism capable of performing fermentation. b. What is the purpose of adding yeast to the bag? 3 Use the balance scale and a weighing boat to weigh out 5 g of sugar. Pour the sugar into the whirl-pak bag. Sugar is a food source for the yeast organisms. c. What is the purpose of adding sugar to the bag? Measure and place 510 ml of water in the 4 1000 ml beaker. Using the heat source (hot plate, d. Why is the bag placed in warm water? microwave, etc.), heat the water in the beaker to approximately 55 C. Warmer 5 water will increase the rate of fermentation. e. How will this lab demonstrate fermentation? Be careful removing and carrying the beaker from the heat source; it may be hot! Aerobic & Anaerobic Conditions, HASPI Medical Biology Lab 11 317
6 7 8 9 10 11 12 Using the graduated cylinder, measure out 10 ml of the warm water from the beaker. Pour the 10 ml of water into the whirl-pak bag with the yeast and sugar. Mix the contents of the bag. Squeeze all of the air out of the bag and wrap it twice around the wire strip. Bend the ends of the strip to hold the bag closed. Place the closed whirl-pak bag into the beaker of remaining warm water. Observe the bag over a 10-minute period. As fermentation occurs, the bag will fill with carbon dioxide produced as the yeast breaks down the sugar molecules. After 10 minutes, completely submerge the whirl-pak bag in the beaker. Mark the water level on the beaker. Submerging the bag and determining how much water is displaced allows you to determine how much gas was produced and trapped in the whirl-pak bag. f. What reaction will occur in the whirl-pak bag? g. In terms of fermentation, why do you think it is important to remove all of the air from the bag? h. What gas is produced when yeast breaks down sugar? i. How will you determine how much carbon dioxide was produced from fermentation over a 10-minute period? 13 Remove and rinse out the whirl-pak bag. 14 To determine how much water was displaced, use one of the following methods: 1. If the beaker is well-marked, subtract 500 ml from the level you marked on the beaker when the whirl-pak bag was submerged. 2. If the beaker is NOT well-marked, add water to the beaker to the level you had marked. Use a graduated cylinder to remove/measure 500 ml of water from the beaker. Also use the graduated cylinder to measure the amount remaining. j. What was the approximate volume of carbon dioxide produced in the bag? k. How might you determine exactly how much carbon dioxide was produced, without the volume of the remaining bag contents? 15 This number represents the volume of carbon dioxide that was produced, and the volume of the bag. 318 Aerobic & Anaerobic Conditions, HASPI Medical Biology Lab 11
Part B. Predicting Fermentation Task In Part B, your team will choose a different sugar source to answer the question: Will yeast perform fermentation with different 1 types of sugar molecules? a. What sugar source did you choose? Response b. Hypothesize whether your sugar source will produce more or less carbon dioxide (than Part A) during fermentation. 2 Choose a sugar source. Your instructor will provide a few options. The source could be in the form of juice, soda, diet soda, or any other liquid or powdered product that may contain sugar. c. What was the approximate volume of carbon dioxide produced in the bag with the new sugar source? d. Compare your results from Part A and Part B. Which one produced more carbon dioxide? Hypothesize why this happened. 3 Use the procedure from Part A, but substitute the 5 g of sugar with the new sugar source. Use 5 g if it is in powder form or 5 ml if it is in a liquid source. (1 g = 1 ml) e. Did your results support your hypothesis from question b? Explain your answer. Aerobic & Anaerobic Conditions, HASPI Medical Biology Lab 11 319
Connections & Applications Your instructor may assign or allow you to choose any of the following activities. As per NGSS/CCSS, these extensions allow students to explore outside activities recommended by the standards. 1. SCIENCE, ART, & MATTER CYCLING: Energy drives the cycling of matter within and between systems. For example, energy is required for the cycling of atoms and molecules in the human body. Calcium, sodium, phosphorous, oxygen, nitrogen, and hydrogen are examples of atoms that cycle through the body. Choose and follow one of these atoms through the human body. Create an artistic visual of the atom s path. The visual can be drawn or computer-generated, and must be in color and labeled. Include the following: a. How the atom enters the body. This will be as part of a larger molecule, and most atoms will be part of more than one molecule. b. Choose at least two body systems, and illustrate how the atom is used and/or moves through that body system. Examples of body systems include the nervous and skeletal systems. c. How the atom exits the body. This may also be part of a larger molecule, which may be different than the molecule from which it entered. 2. RESEARCHING LACTIC ACID: In the body, a by-product of anaerobic respiration is lactic acid. Use the Internet to research and answer the following questions about exercise and lactic acid. Cite your sources. a. What is the chemical formula for lactic acid? b. What is the chemical equation for anaerobic respiration in the human body? c. How much (in percentage) more energy is produced by aerobic respiration than anaerobic respiration? d. How and where does lactic acid build up in the body? e. How is lactic acid removed from the body? f. What is oxygen debt, and how does it affect the production of lactic acid? g. List and explain three types of exercise that can cause the body to rely on anaerobic respiration for energy. h. What causes lactic acidosis, and what are the symptoms? 3. EXTENDING THE EXPERIMENT: Choose three additional substances for Lab 11b, Part B to test. Rinse out and reuse the whirl-pak bag; yeast can be obtained from any grocery store. Using the same experiment model, test each substance and compare to the results from Lab 11b. Create a lab report that includes a question, your hypothesis for each substance, materials, summary of the procedure, and a table that summarizes the results. Resources & References Annenberg Foundation. 2014. Section 3: Energy Flow Through Ecosystems. The Habitable Planet, Annenberg Learner, http://www.learner.org/courses/envsci/unit/text.php?unit=4&secnum=3. Farabee, M.J. 2007. Cellular Metabolism and Fermentation. http://www2.estrellamountain.edu/faculty/farabee/biobk/biobookglyc.html. 320 Aerobic & Anaerobic Conditions, HASPI Medical Biology Lab 11