Respiration Review Lab Overview: We eat food to provide our bodies with energy. However, trying to use food molecules like glucose to run our bodies is like trying to run a car wash with a five dollar bill. Your cells can only use the chemical bond energy stored in ATP molecules to run cellular operations just as the car wash will only run on dollars or quarters. Therefore, the cell must change food molecules like glucose into usable form --- ATP. This process is called cellular respiration. Let s compare the burning of glucose in the body to the burning of a candle. Glucose molecules provide energy for the body just like the candle wax provides energy for the burning flames. The following experiments will provide some information about processes involved in the burning of a candle that also apply to the burning of glucose in the body. Materials per Group: Large candle 500 ml Erlenmeyer Flask Matches Aluminum pie plates Water Bromothymol Blue TAKS Objective 2 page 25
Experiment #1 Candle Matches 500 ml Erlenmeyer Flask Aluminum Pie Plate Procedure/Observations: 1. Light the candle and allow it to burn. a. What provided the spark to start the candle burning? b. What provides the fuel for the burning candle? 2. Is the burning candle giving off any type of energy? If so, what kind(s) of energy are being released? 3. Place the beaker or flask over the candle. What happens? 4. What caused the candle to go out? 5. What gas is necessary for the candle to burn efficiently? 6. What provides the spark to get cellular respiration started in the cell? 7. Is energy released when glucose is burned in the cell? If so, what kind of energy is released? 8. Why isn t heat released in large quantities in the cell? 9. Is the same gas necessary to burn glucose efficiently in the body as is needed to burn the candle efficiently? 10. What is the gas that is needed to break down glucose into ATP efficiently? 11. Where in the cell is glucose broken down in the presence of this gas? 12. What is the name for this type of cellular respiration? 13. How many ATP s (net) can be gained if a glucose molecule is completely broken down with oxygen? 14. If oxygen was not present, how many ATP s (net) could be gained from a glucose molecule being broken down? TAKS Objective 2 page 26
15. What is the term for the breakdown of glucose into ATP without oxygen? 16. Where in the cell does the process described in #15 take place? 17. Explain why it is so important that oxygen be present to breakdown glucose. 18. How long can the candle burn without oxygen? 19. How long do you think a cell can run without oxygen? TAKS Objective 2 page 27
Experiment #2 Candle Matches 500 ml Erlenmeyer Flask Bromothymol Blue Aluminum Pie Plate Procedures/Observations: 1. Light the candle again and allow it to burn. 2. Place the flask over the candle and leave it until the candle goes out. 3. Slide the flask quickly up and over the candle and cover the bottom of the flask with your hand, trying not to let any of the contents escape. Turn the flask right side up. 4. Carefully move your hand from the top of the flask just enough to add 2 drops of Bromothymol Blue then cover the top completely again. 5. What color was the Bromothymol Blue to begin with? 6. What color did the Bromothymol Blue turn when placed in the beaker? (You may have to swirl the liquid and wait a minute or two for a change.) 7. Do you notice any water vapor on the inside of the flask? 8. Is water also a waste product (by product) of cellular respiration? 9. Bromothymol Blue is a ph indicator. Carbonic acid forms in the presence of water and high concentrations of what gas? 10. What gas was given off as a waste product of the burning candle? 11. What gas is given off as a waste product of cellular respiration? TAKS Objective 2 page 28
Experiment #3 Candle Matches 500 ml Erlenmeyer Flask Water Aluminum Pie Plate Procedures/Observations: 1. Pour enough water in the bottom of the pan to fill the pan at least half-full. 2. Light the candle and let it burn. Set the base of the candle in to the water in the middle of the pan and let it continue to burn. 3. Place the flask over the candle, submerging it in the water. 4. What happens when the candle goes out? 5. What was removed from the air in the flask to allow space for the water to come in? 6. Carbon dioxide is released into the air during the burning of the candle. However, much of this carbon dioxide becomes dissolved in the water to form carbonic acid. This provides even more space for the water to rush in. Conclusions: 1. Write the balanced, general formula for cellular respiration. 2., and are the materials necessary for respiration to take place in the cell. 3.,, and ( ) are given off during cellular respiration. TAKS Objective 2 page 29