9.1 Cellular Respiration: An Overview, Exercises of Cell Biology

Download 9.1 Cellular Respiration: An Overview and more Exercises Cell Biology in PDF only on Docsity! Name Class Date 9.1 Cellular Respiration: An Overview Lesson Objectives Explain where organisms get the energy they need for life processes. Define cellular respiration. Compare photosynthesis and cellular respiration. Lesson Summary Chemical Energy and Food Chemical energy is stored in food molecules. Energy is released when chemical bonds in food molecules are broken. Energy is measured in a unit called a calorie, the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius. Fats store more energy per gram than do carbohydrates and proteins. Overview of Cellular Respiration Cellular respiration is the process that releases energy from food in the presence of oxygen. Cellular respiration captures the energy from food in three main stages: • glycolysis • the Krebs cycle • the electron transport chain Glycolysis does not require oxygen. The Krebs cycle and electron transport chain both require oxygen. • Aerobic pathways are processes that require oxygen. • Anaerobic pathways are processes that occur without oxygen. Comparing Photosynthesis and Cellular Respiration The energy in photosynthesis and cellular respiration flows in opposite directions. Their equations are the reverse of each other. Photosynthesis removes carbon dioxide from the atmosphere, and cellular respiration puts it back. Photosynthesis releases oxygen into the atmosphere, and cellular respiration uses oxygen to release energy from food. Chemical Energy and Food For Questions 1–4, complete each statement by writing the correct word or words. 1. A calorie is a unit of . 2. The Calorie used on food labels is equal to calories. 3. A Calorie is also referred to as a . 4. Cells use the energy stored in chemical bonds of foods to produce compounds that directly power the cell’s activities, such as . 130 Name Class Date Overview of Cellular Respiration For Questions 5–10, complete each statement by writing the correct word or words. 5. The equation that summarizes cellular respiration, using chemical formulas, is . 6. If cellular respiration took place in just one step, most of the would be lost in the form of light and . 7. Cellular respiration begins with a pathway called , which takes place in the of the cell. 8. At the end of glycolysis, about percent of the chemical energy is locked in the bonds of the molecule. 9. Cellular respiration continues in the of the cell with the and electron transport chain. 10. The pathways of cellular respiration that require oxygen are said to be . Pathways that do not require oxygen are said to be . 11. Complete the illustration by adding labels for the three main stages of cellular respiration. 131 THINK VISUALLY Name Class Date Glycolysis 1. Complete the diagram by writing on the lines provided the names and numbers of molecules used and produced during glycolysis. 2. Why is it an investment for the cell to use two ATP at the beginning of glycolysis? 3. What are two advantages of glycolysis? 134 THINK VISUALLY Name Class Date The Krebs Cycle For Questions 4–7, write True if the statement is true. If the statement is false, change the underlined word or words to make the statement true. 4. The pyruvic acid produced in glycolysis enters the chloroplasts if oxygen is present in a cell. 5. In the matrix, pyruvic acid is converted to lactic acid before the Krebs cycle begins. 6. The compound that joins with a 4-carbon molecule in the Krebs cycle is called acetyl-CoA. 7. Carbon dioxide is the only product of the Krebs cycle that is not re-used or used in other stages of cellular respiration. 8. Complete the flowchart to show which of the Krebs cycle’s many products go on to the third stage of cellular respiration. Electron Transport and ATP Synthesis For Questions 9–14, complete each statement by writing the correct word or words. 9. In eukaryotes, the electron transport chain is composed of a series of electron carriers located in the of the mitochondrion. 10. In prokaryotes, the electron transport chain is in the . 11. serves as the final electron acceptor of the electron transport chain. 12. and pass high-energy electrons to the electron transport chain. 13. The transfer of high-energy electrons down the electron transport chain causes to be transported across the mitochondrial membrane. 14. ATP synthases produce the force needed to add one to each ADP molecule by spinning when hydrogen ions flow through them. 135 Krebs Cycle Electron Transport Chain Name Class Date The Totals 15. How many ATP molecules per glucose molecule does a cell gain from each of the three stages of cellular respiration? 16. Besides glucose, what other kinds of molecules can be used to produce ATP in cellular respiration? 17. Why is cellular respiration considered an efficient process? 18. Where does the heat that warms your body come from? Explain your answer. 136 Apply the Big idea Name Class Date Energy and Exercise 10. What are three main sources of ATP available for human muscle cells? 11. During a race, how do your muscle cells produce ATP after the store of ATP in muscles is used? 12. Why does a sprinter have an oxygen debt to repay after the race is over? 13. A runner needs more energy for a longer race. How does the body generate the necessary ATP? 14. Why are aerobic forms of exercise so beneficial for weight control? 15. Compare and contrast the role of fermentation and cellular respiration in the actual production of ATP. In your response, consider which process produces ATP and which process contributes to its production. 139 Apply the Big idea Multiple Choice Write the letter that best answers the question or completes the statement on the line provided. _____ 1. How do organisms get the energy they need? a. by burning food molecules and releasing their energy as heat b. by breathing oxygen into the lungs and combining it with carbon dioxide c. by breaking down food molecules gradually and capturing their chemical energy d. by using the sun’s energy to break down food molecules and form chemicals _____ 2. Which of the following is NOT a stage of cellular respiration? a. fermentation c. glycolysis b. electron transport d. Krebs cycle _____ 3. Cellular respiration is called an aerobic process because it requires a. light. c. oxygen. b. exercise. d. glucose. _____ 4. Photosynthesis is to chloroplasts as cellular respiration is to a. chloroplasts. c. mitochondria. b. cytoplasm. d. nuclei. _____ 5. The products of photosynthesis are the a. products of cellular respiration. b. reactants of cellular respiration. c. products of glycolysis. d. reactants of fermentation. _____ 6. Glycolysis provides a cell with a net gain of a. 2 ATP molecules. c. 18 ATP molecules. b. 4 ATP molecules. d. 36 ATP molecules. _____ 7. Glycolysis requires a. ATP. c. sunlight. b. oxygen. d. NADP+. _____ 8. The Krebs cycle starts with a. lactic acid and yields carbon dioxide. b. glucose and yields ATP. c. pyruvic acid and yields lactic acid. d. pyruvic acid and yields carbon dioxide. _____ 9. In eukaryotes, electron transport occurs in the a. inner mitochondrial membrane. b. nucleus. c. cell membrane. d. cytoplasm. _____ 10. Which of the following pass high-energy electrons to the electron transport chain? a. NADH and FADH2 b. ATP and ADP c. citric acid d. acetyl–CoA _____ 11. Cellular respiration uses 1 molecule of glucose to produce approximately a. 2 ATP molecules. b. 4 ATP molecules. c. 32 ATP molecules. d. 36 ATP molecules. _____ 12. Lactic acid fermentation occurs in a. bread dough. b. any environment containing oxygen. c. muscle cells. d. mitochondria. _____ 13. During fermentation, a. NAD+ is regenerated, allowing glycolysis to continue. b. glucose is split into 3 pyruvic acid molecules. c. oxygen is required. d. carbon dioxide is produced. _____ 14. Breathing heavily after running a race is your body’s way of a. making more citric acid. c. restarting glycolysis. b. repaying an oxygen debt. d. stopping the electron transport chain. _____ 15. The energy needed to win a 1-minute footrace is produced mostly by a. lactic acid fermentation. c. using up stores of ATP b. cellular respiration. d. breaking down fats. Completion Complete each statement on the line provided. 16. Photosynthesis occurs only in plants, algae, and some bacteria. In contrast, occurs in all eukaryotic cells. 17. Glycolysis rearranges a 6-carbon glucose molecule into two 3-carbon molecules of . 18. When pass through ATP synthase, ATP molecules are produced from ADP molecules. 19. Glycolysis alone nets only molecules of ATP from each glucose molecule. 20. The body gets rid of lactic acid in a chemical pathway that requires . 172 Essay Write the answer to each question in the space provided. 31. What would happen if all the energy in glucose were released in just one step instead of gradually as it is in cellular respiration? How is the gradual process of cellular respiration advantageous to the cell? 32. Describe the main steps and the results of the Krebs cycle. 33. Identify the electron carriers of cellular respiration. Discuss the relationship between the electron carriers and the electron transport chain. 34. People who suffer from a heart attack often have an increased ratio of lactic acid to pyruvic acid in their hearts. What does this observation say about the availability of oxygen in the heart muscle cells of someone who has had a heart attack? How could you use this information to screen people who might be at risk for a heart attack? 35. Why does lactic acid fermentation “kick in” during a sprint race?