Cells and Energy Answer Key SECTION 1. CHEMICAL ENERGY AND ATP 1. molecule; food molecules 2. high-energy; lower-energy 3. phosphate group 4. a; d; b; c 5. b; e 6. c; d 7. a; f 8. chemical energy; light energy 9. three; two 10. chemical; molecules SECTION 2. OVERVIEW OF PHOTOSYNTHESIS 1. chemical energy 2. light energy; chemical energy 3. visible light 4. photosynthesis 5. stroma; grana 6. grana 7. Equation: 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 8. 6CO 2 and 6H 2 O 9. 6O 2 and C 6 H 12 O 6 10. b 11. require light; energy 12. do not require light; sugars 13. Refer to Figure 2.2 for a visual answer. The four steps are: d, a, b, c 14. energy; sugars 15. green 16. independent SECTION 3. PHOTOSYNTHESIS IN DETAIL 1. capture; transfer 2. molecules 3. ATP; NADPH 4. b, g, d, f, c, e, a 5. carbon dioxide 6. 1 b; 2 d; A a; 3 e; 4 c 7. proteins 8. synthesizes 9. with no beginning or end. SECTION 4. OVERVIEW OF CELLULAR RESPIRATION 1. energy; oxygen 2. oxygen 3. mitochondria 4. glucose; ATP 5. b; c 6. a; c 7. Equation: C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O 8. 6O 2 and C 6 H 12 O 6 9. 6CO 2 and 6H 2 O 10. d 11. Refer to Figure 4.2 for a visual answer. The four steps are: d, b, a, c 12. sugar 13. oxygen 14. break down SECTION 5. CELLULAR RESPIRATION IN DETAIL 1. glucose 2. Pyruvate and NADH; ATP 3. two; four 4. c 5. c, b, a, d, e 6. inner 7. electrons; hydrogen ions 8. c, d, b, a 9. electrons SECTION 6. FERMENTATION 1. ATP 2. electrons 3. hard exercise 4. oxygen 5. two 6. For a visual answer, refer to the lactic acid fermentation diagram in Section 6. The order of the four steps is: d, b, c, a 7. For a visual answer, refer to the alcoholic fermentation diagram in Section 6. The order of the four steps is: c, a, d, b Holt McDougal Biology i Cells and Energy
continued 8. Uses pyruvate and NADH = Both; Recycles NAD + to glycolysis = Both; Produces Lactic Acid = Lactic acid fermentation; Produces alcohol and carbon dioxide = Alcoholic Fermentation. 9. cheese, yogurt 10. bread 11. carbon dioxide 12. waste product; muscles Holt McDougal Biology ii Cells and Energy
Section 1: Chemical Energy and ATP KEY CONCEPT All cells need chemical energy. VOCABULARY ATP ADP chemosynthesis MAIN IDEA: The chemical energy used for most cell processes is carried by ATP. Circle the word or phrase that best completes the statement. 1. All cells use adenosine triphosphate (ATP) for energy. ATP is a molecule / organelle that transfers energy from the breakdown of ADP / food molecules to cell processes. 2. ATP is a high-energy / low-energy molecule that is converted into higher-energy / lower-energy ADP when a phosphate group is removed and energy is released. 3. ADP is converted back into ATP by the addition of a phosphate group / food molecule. 4. Put the letter of the appropriate statement into each box of the cycle diagram below to show the relationship between ATP and ADP. a. High-energy adenosine triphosphate (ATP) b. Lower-energy adenosine diphosphate (ADP) c. Energy added from breakdown of carbon-based molecules, phosphate added d. Phosphate removed, energy released Holt McDougal Biology 1 Cells and Energy Section 1: Chemical Energy and ATP
continued MAIN IDEA: Organisms break down carbon-based molecules to produce ATP. Put the letter for each of the following six statements into the appropriate list to identify the roles of different types of molecules when they are broken down to make ATP. a. molecules least likely to be broken down b. molecules most commonly broken down c. molecules that store most of the energy in a person s body d. triglyceride yields about 146 ATP e. glucose yields about 36 ATP f. store about the same amount of energy as carbohydrates Type of Molecule 5. Carbohydrates Role in ATP Production 4 calories per mg (4 Calories per gram) 6. Lipids 9 calories per mg (9 Calories per gram) 7. Proteins 9 calories 4 calories per mg (4 Calories per gram) MAIN IDEA: A few types of organisms do not need sunlight and photosynthesis as a source of energy. Circle the word or phrase that best completes the statement. 8. Chemosynthesis is a process by which some organisms use chemical energy / light energy instead of chemical energy / light energy to make energy-storing carbon-based molecules. Holt McDougal Biology 2 Cells and Energy Section 1: Chemical Energy and ATP
continued Vocabulary Check Fill in each blank with the word or phrase that best completes the sentence. 9. The prefix tri- means three, and the prefix di- means two. Therefore, adenosine triphosphate (ATP) has phosphate groups, and adenosine diphosphate (ADP) has phosphate groups. 10. The prefix chemo- means chemical, and synthesis comes from a Greek word that means to put together. Therefore, chemosynthesis means to put together with chemicals. In chemosynthesis, energy is used to produce carbon-based that store energy. Holt McDougal Biology 3 Cells and Energy Section 1: Chemical Energy and ATP
Section 2: Overview of Photosynthesis KEY CONCEPT The overall process of photosynthesis produces sugars that store chemical energy. VOCABULARY photosynthesis chlorophyll thylakoid light-dependent reactions light-independent reactions MAIN IDEA: Photosynthetic organisms are producers. Circle the word or phrase that best completes the statement. 1. Some organisms are called producers because they produce the source of chemical energy / light energy for themselves and for other organisms. 2. Photosynthesis captures chemical energy / light energy to make sugars that store chemical energy / light energy. 3. Chlorophyll is a molecule in chloroplasts that absorbs some of the energy in visible light / ultraviolet light. MAIN IDEA: Photosynthesis in plants occurs in chloroplasts. 4. Chloroplasts are membrane-bound organelles where takes place in plants. 5. Photosynthesis takes place in two parts of a chloroplast: the and the. 6. Thylakoids are coin-shaped, membrane-enclosed compartments inside the. 7. The overall process of photosynthesis can be written as a chemical equation. Fill in the blanks in the equation below using the appropriate compound from the box. 6O 2 6CO 2 6H 2 O C 6 H 12 O 6 + + 8. The two reactants in the photosynthesis equation are and. 9. The two products in the photosynthesis equation are and. Holt McDougal Biology 4 Cells and Energy Section 3: Photosynthesis in Detail
continued 10. Why is the photosynthesis equation often written with several arrows? a. Because many enzymes are added to the reactants to make the products. b. Because many chemical reactions occur with the help of many enzymes. c Because many reactants can enter into the photosynthesis reaction. d. Because many products can be made from the photosynthesis reaction. Circle the word or phrase that best completes the statement. 11. The light-dependent reactions require light / do not require light, and they absorb and transfer sugars / energy. 12. The light-independent reactions require light / do not require light, and they build sugars / energy. 13. Use the space below to sketch a chloroplast. Label the grana, thylakoids, and stroma. Indicate where each of the following steps of the photosynthetic process occurs. a. Energy carried along the thylakoid membrane is transferred to molecules that carry energy to the light-independent reactions. b. Carbon dioxide is added to a cycle of chemical reactions to build larger molecules. c. A six-carbon simple sugar (usually glucose; C 6 H 12 O 6 ) is formed. d. Energy from sunlight is absorbed and transferred along the thylakoid membrane. Water molecules are broken down and oxygen is released. Photosynthesis Holt McDougal Biology 5 Cells and Energy Section 3: Photosynthesis in Detail
continued Vocabulary Check Fill in each blank with the word or phrase that best completes the sentence. 14. The prefix photo- means light, and synthesis means to put together. During photosynthesis, from light is used to put together. 15. The prefix chloro- means green, and the suffix -phyll means leaf. Therefore, chlorophyll is the light-absorbing molecule that makes leaves look. 16. The prefix in- means not. Therefore, the reactions in photosynthesis that do not require light are called light-. Main idea: THE SECOND STAGE OF PHOTOSYNTHESIS USES ENERGY FROM THE FIRST STAGE TO MAKE SUGARS. 5. The Calvin cycle uses energy from the light-dependent reactions to convert into sugars. 6. Using the diagram on the next page, put the letter from each of the following statements into the appropriate box to show the four steps of the Calvin cycle. a. A three-carbon molecule exits the cycle. Other three-carbon molecules stay in the cycle. b. Carbon dioxide is added to the Calvin cycle. c. Energy is used to convert the remaining three-carbon molecules into fivecarbon molecules. d. Energy is used to split six-carbon molecules. Three-carbon molecules are formed and rearranged. e. When two three-carbon molecules have left the cycle they bond to form a six-carbon sugar (glucose). Holt McDougal Biology 6 Cells and Energy Section 3: Photosynthesis in Detail
continued 1. 4. 2. A. 3. Vocabulary Check Circle the word or phrase that best completes the statement. 7. The electron transport chain is a series of proteins / carbohydrates in the thylakoid membrane along which energized electrons travel. 8. The first part of an enzyme s name tells you about its function. All enzymes end with the suffix -ase. Therefore, ATP synthase is an enzyme that synthesizes / synchronizes ATP. 9. The word cycle tells you that the chemical reactions of the Calvin cycle go from one to another with a beginning and an end / with no beginning or end. Holt McDougal Biology 7 Cells and Energy Section 3: Photosynthesis in Detail
Section 4: Overview of Cellular Respiration KEY CONCEPT The overall process of cellular respiration converts sugar into ATP using oxygen. VOCABULARY cellular respiration aerobic glycolysis anaerobic Krebs cycle MAIN IDEA: Cellular respiration makes ATP by breaking down sugars. Circle the word or phrase that best completes the statement. 1. Cellular respiration is a process that releases glucose / energy from sugars and other carbon-based molecules to make ATP when oxygen / carbon dioxide is present. 2. Cellular respiration is called an aerobic process, because it needs oxygen / carbon dioxide to take place. 3. Cellular respiration takes place in the chloroplasts / mitochondria. 4. During glycolysis, one molecule of glucose / protein is split into two threecarbon molecules and two ADP / ATP are formed. MAIN IDEA: Cellular respiration makes ATP by breaking down sugars. 5. Circle the two ways in which cellular respiration seems to be the opposite of photosynthesis. a. The reactions occur at either end of the chloroplast. b. The overall chemical equations are the reverse of each other. c. Cellular respiration breaks down sugars to make ATP, and photosynthesis uses ATP to make sugars. d. Cellular respiration produces oxygen, and photosynthesis produces carbon dioxide. 6. Circle the two parts of a mitochondrion where cellular respiration takes place. a. matrix b stroma c. inner mitochondrial membrane d. outer mitochondrial membrane Holt McDougal Biology 8 Cells and Energy Section 4: Overview of Cellular Respiration
continued 7. The overall process of cellular respiration can be written as a chemical equation. Fill in the blanks in the equation below using the appropriate compound from the box. 6O 2 6CO 2 6H 2 O C 6 H 12 O 6 Cellular Respiration + + 8. The two reactants in the cellular respiration equation are and. 9. The two products in the cellular respiration equation are and. 10. Why is the cellular respiration equation written with several arrows? a. Because a series of products result from the reaction. b. Because a series of reactants enter into the reaction. c. Because a series of chemicals is added to the process. d. Because a series of chemical reactions occurs. 11. Use the space below to sketch a mitochondrion. Label the matrix and inner membrane. Indicate where each of the following steps of the cellular respiration process occurs. a. Energized electrons are passed along the electron transport chain in the inner mitochondrial membrane. b. Energy is transferred to the second stage of cellular respiration (the electron transport chain). c. A large number of ATP are formed. Oxygen picks up electrons, and water is released as a waste product. d. Three-carbon molecules enter the Krebs cycle and are broken down. ATP and other energy-carrying molecules are formed. Carbon dioxide is released as a waste product. Holt McDougal Biology 9 Cells and Energy Section 4: Overview of Cellular Respiration
continued Vocabulary Check Fill in the blank with the word or phrase that best completes the sentence. 12. The prefix glyco- comes from a Greek word that means sweet. The suffix -lysis comes from a Greek word that means to loosen. Therefore, during glycolysis, a is broken down (or loosened ). 13. Glycolysis is an anaerobic process, because it takes place without. 14. During the Krebs cycle, chemical reactions carbonbased molecules. Holt McDougal Biology 10 Cells and Energy Section 4: Overview of Cellular Respiration
Section 6: Fermentation KEY CONCEPT Fermentation allows the production of a small amount of ATP without oxygen. VOCABULARY fermentation lactic acid MAIN IDEA: Fermentation allows glycolysis to continue. 1. Fermentation is important, because it allows glycolysis to continue making when oxygen is unavailable for cellular respiration. 2. Fermentation removes from NADH and recycles NAD + to glycolysis. 3. Fermentation takes place in your muscle cells during, when not enough oxygen is available. 4. Fermentation is an anaerobic process, because it occurs without. 5. Fermentation is involved in the production of ATP by allowing glycolysis to take place. Glycolysis yields net ATP. 6. In the space below, draw the process of lactic acid fermentation and label it with the statements listed. a. NAD + is recycled to glycolysis. b. NADH is used to convert pyruvate into lactic acid. c. NADH is changed into NAD +. d. Pyruvate and glycolysis enter fermentation. Lactic Acid Fermentation Holt McDougal Biology 11 Cells and Energy Section 6: Fermentation
continued MAIN IDEA: Fermentation and its products are important in several ways. 7. In the space below, draw the process of alcoholic fermentation and label it with the statements listed. a. NADH is used to convert pyruvate into alcohol and carbon dioxide. b. NAD + is recycled to glycolysis. c. Pyruvate and glycolysis enter fermentation. d. NADH is changed into NAD +. Alcoholic Fermentation 8. Place a check mark in the appropriate boxes below to show how lactic acid fermentation and alcoholic fermentation are similar and how they are different. Uses pyruvate and NADH Recycles NAD + to glycolysis Produces lactic acid Produces alcohol and carbon dioxide Lactic Acid Fermentation Alcoholic Fermentation Both Holt McDougal Biology 12 Cells and Energy Section 6: Fermentation
continued 9. Name one commercial use of lactic acid fermentation. 10. Name one commercial use of alcoholic fermentation. Vocabulary Check Circle the word or phrase that best completes the statement. 11. The term fermentation is based on a word that means to bubble. This meaning is related to the fermentation process, because bubbles of carbon dioxide / oxygen are produced during alcoholic fermentation. 12. Lactic acid is the three-carbon reactant / waste product of lactic acid fermentation. It causes a burning feeling in your muscles / blood vessels during exercise Holt McDougal Biology 13 Cells and Energy Section 6: Fermentation