Cellular Respiration and Photosynthesis, Exams of Biology

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BIOD 121 Portage Learning Module

5 Exam

Question 1 Which of the following best describes the primary function of enzymes in biological systems? A) To increase the temperature of reactions B) To act as a substrate for reactions C) To lower the activation energy of reactions D) To change the pH of the reaction environment Correct Answer: C) To lower the activation energy of reactions

Question 2 What is the term for the region of an enzyme where substrate molecules bind and undergo a chemical reaction? A) Active site B) Allosteric site C) Catalytic site D) Substrate binding site Correct Answer: A) Active site Question 3 Which factor does NOT affect enzyme activity? A) Temperature B) pH C) Concentration of substrate D) Concentration of product Correct Answer: D) Concentration of product Question 4 Which of the following statements is true regarding enzyme inhibitors? A) They increase the rate of enzyme reactions. B) They bind to the active site, preventing substrate binding. C) They are always reversible. D) They are necessary for all enzyme reactions. Correct Answer: B) They bind to the active site, preventing substrate binding.

Question 5 In the context of cellular respiration, which process occurs in the mitochondria? A) Glycolysis B) Krebs cycle C) Fermentation D) Electron transport chain Correct Answer: B) Krebs cycle Question 6 What is the primary purpose of the citric acid cycle (Krebs cycle)? A) To produce ATP directly B) To generate electron carriers for the electron transport chain C) To break down glucose into pyruvate D) To convert fatty acids into acetyl-CoA Correct Answer: B) To generate electron carriers for the electron transport chain Question 7 Which of the following molecules serves as the final electron acceptor in aerobic respiration? A) Lactic acid B) Oxygen C) Carbon dioxide D) Water Correct Answer: B) Oxygen Question 8

What is the end product of glycolysis? A) Glucose B) Pyruvate C) Acetyl-CoA D) Lactate Correct Answer: B) Pyruvate Question 9 In which part of the cell does glycolysis take place? A) Mitochondria B) Nucleus C) Cytoplasm D) Endoplasmic reticulum Correct Answer: C) Cytoplasm Question 10 Which of the following best describes oxidative phosphorylation? A) It involves the synthesis of glucose from carbon dioxide. B) It is the process of generating ATP through the electron transport chain and chemiosmosis. C) It occurs only in the absence of oxygen. D) It is the first step in the breakdown of glucose. Correct Answer: B) It is the process of generating ATP through the electron transport chain and chemiosmosis.Question 11 Which enzyme is primarily responsible for the conversion of glucose to glucose-6- phosphate during the first step of glycolysis?

A) Hexokinase B) Phosphofructokinase C) Aldolase D) Pyruvate kinase Correct Answer: A) Hexokinase Question 12 What is the role of NAD+ in cellular respiration? A) It acts as a substrate. B) It serves as an electron carrier. C) It inhibits enzyme activity. D) It is involved in ATP synthesis. Correct Answer: B) It serves as an electron carrier. Question 13 Which of the following processes occurs in anaerobic conditions? A) Krebs cycle B) Electron transport chain C) Lactic acid fermentation D) Oxidative phosphorylation Correct Answer: C) Lactic acid fermentation Question 14 During the electron transport chain, what is the main function of ATP synthase? A) To generate heat

B) To transport electrons C) To synthesize ATP from ADP and inorganic phosphate D) To pump protons out of the mitochondria Correct Answer: C) To synthesize ATP from ADP and inorganic phosphate Question 15 What is produced as a byproduct of alcoholic fermentation? A) Lactic acid B) Ethanol C) Oxygen D) Glucose Correct Answer: B) Ethanol Question 16 Which of the following statements about photosynthesis is true? A) It occurs only in plants. B) It converts light energy into chemical energy. C) It occurs only during the day. D) It produces carbon dioxide as a primary product. Correct Answer: B) It converts light energy into chemical energy. Question 17 In the light-dependent reactions of photosynthesis, what is the primary source of energy? A) Carbon dioxide B) Water

C) Glucose D) Sunlight Correct Answer: D) Sunlight Question 18 Which of the following is a product of the light-dependent reactions of photosynthesis? A) Oxygen B) Glucose C) ATP D) Both A and C Correct Answer: D) Both A and C Question 19 What is the role of RuBisCO in the Calvin cycle? A) To convert ATP to ADP B) To fix carbon dioxide C) To produce glucose D) To synthesize NADPH Correct Answer: B) To fix carbon dioxide Question 20 Which pigment is primarily responsible for capturing light energy in photosynthesis? A) Carotenoids B) Chlorophyll a C) Chlorophyll b

D) Xanthophyll Correct Answer: B) Chlorophyll a Question 21 How many molecules of CO₂ are required to produce one molecule of glucose in the Calvin cycle? A) 1 B) 2 C) 3 D) 6 Correct Answer: D) 6 Question 22 What is the primary purpose of the Calvin cycle? A) To produce ATP B) To fix carbon into organic molecules C) To split water molecules D) To generate oxygen Correct Answer: B) To fix carbon into organic molecules Question 23 What is the main energy currency of the cell? A) DNA B) ATP C) NADH D) FADH₂

Correct Answer: B) ATP Question 24 Which molecule is formed during the transition step between glycolysis and the Krebs cycle? A) Acetyl-CoA B) Pyruvate C) Oxaloacetate D) Citrate Correct Answer: A) Acetyl-CoA Question 25 Which metabolic pathway occurs in both the cytoplasm and mitochondria? A) Glycolysis B) Krebs cycle C) Electron transport chain D) Fermentation Correct Answer: A) GlycolysisQuestion 26 What is the main function of coenzymes in enzymatic reactions? A) To act as substrates B) To enhance enzyme activity by assisting in substrate binding C) To inhibit enzyme activity D) To provide energy Correct Answer: B) To enhance enzyme activity by assisting in substrate binding

Question 27 In which part of the chloroplast do the light-dependent reactions occur? A) Stroma B) Thylakoid membranes C) Inner membrane D) Outer membrane Correct Answer: B) Thylakoid membranes Question 28 Which of the following best describes fermentation? A) An aerobic process that produces ATP B) A process that produces ATP without oxygen C) A process that occurs only in prokaryotes D) A step in the Krebs cycle Correct Answer: B) A process that produces ATP without oxygen Question 29 What is the primary role of the proton gradient in oxidative phosphorylation? A) To stabilize ATP molecules B) To drive the synthesis of ATP via ATP synthase C) To transport electrons through the electron transport chain D) To convert glucose into pyruvate Correct Answer: B) To drive the synthesis of ATP via ATP synthase Question 30 Which of the following is NOT a product of the Krebs cycle?

A) NADH

B) FADH₂

C) ATP

D) Glucose Correct Answer: D) Glucose Question 31 What is the significance of the electron transport chain in cellular respiration? A) It synthesizes glucose from carbon dioxide. B) It generates a proton gradient to produce ATP. C) It produces pyruvate from glucose. D) It breaks down fatty acids into acetyl-CoA. Correct Answer: B) It generates a proton gradient to produce ATP. Question 32 What is produced during the light-independent reactions (Calvin cycle) of photosynthesis? A) Oxygen B) ATP C) Glucose D) NADPH Correct Answer: C) Glucose Question 33 Which enzyme catalyzes the conversion of 3-phosphoglycerate to glyceraldehyde-3- phosphate in the Calvin cycle?

A) RuBisCO B) Phosphoglycerate kinase C) Glyceraldehyde-3-phosphate dehydrogenase D) Ribulose bisphosphate carboxylase Correct Answer: C) Glyceraldehyde-3-phosphate dehydrogenase Question 34 Which of the following factors can denature an enzyme? A) Low temperature B) High pH C) High salt concentration D) Both B and C Correct Answer: D) Both B and C Question 35 What is the primary purpose of the light-harvesting complexes in photosynthesis? A) To generate ATP B) To absorb and transfer light energy to the reaction center C) To fix carbon dioxide D) To produce oxygen Correct Answer: B) To absorb and transfer light energy to the reaction center Question 36 Which of the following pathways generates the most ATP? A) Glycolysis

B) Krebs cycle C) Electron transport chain D) Fermentation Correct Answer: C) Electron transport chain Question 37 What is the end product of the Krebs cycle after one turn? A) Acetyl-CoA B) Oxaloacetate C) NADH D) Citric acid Correct Answer: C) NADH Question 38 Which cellular process is the primary source of energy for cellular activities? A) Photosynthesis B) Cellular respiration C) Fermentation D) Glycolysis Correct Answer: B) Cellular respiration Question 39 In which cellular organelle does the Krebs cycle take place? A) Cytoplasm B) Mitochondria C) Nucleus

D) Chloroplast Correct Answer: B) Mitochondria Question 40 What role does oxygen play in cellular respiration? A) It is a substrate for glycolysis. B) It serves as the final electron acceptor in the electron transport chain. C) It is produced during fermentation. D) It is converted into glucose. Correct Answer: B) It serves as the final electron acceptor in the electron transport chain.Question 41 Which of the following describes the process of substrate-level phosphorylation? A) It occurs in the mitochondria during oxidative phosphorylation. B) It involves the direct transfer of a phosphate group to ADP to form ATP. C) It requires oxygen to occur. D) It occurs exclusively in the Calvin cycle. Correct Answer: B) It involves the direct transfer of a phosphate group to ADP to form ATP. Question 42 What molecule acts as the main energy carrier in cells? A) ADP B) FADH₂ C) ATP D) NADH

Correct Answer: C) ATP Question 43 Which of the following statements about photosynthesis is incorrect? A) It converts light energy into chemical energy. B) It produces glucose as the primary product. C) It releases carbon dioxide as a byproduct. D) It occurs in chloroplasts. Correct Answer: C) It releases carbon dioxide as a byproduct. Question 44 During which phase of cellular respiration is the majority of ATP produced? A) Glycolysis B) Krebs cycle C) Electron transport chain D) Fermentation Correct Answer: C) Electron transport chain Question 45 What happens to pyruvate after glycolysis if oxygen is present? A) It is converted to lactate. B) It enters the Krebs cycle as acetyl-CoA. C) It is used to produce glucose. D) It undergoes fermentation. Correct Answer: B) It enters the Krebs cycle as acetyl-CoA.

Question 46 Which of the following components is NOT part of the chloroplast? A) Stroma B) Thylakoids C) Granum D) Golgi apparatus Correct Answer: D) Golgi apparatus Question 47 What is the primary purpose of the Calvin cycle in photosynthesis? A) To produce ATP B) To fix carbon dioxide into organic compounds C) To generate oxygen D) To synthesize glucose directly Correct Answer: B) To fix carbon dioxide into organic compounds Question 48 In the Krebs cycle, which molecule is regenerated to allow the cycle to continue? A) Acetyl-CoA B) Oxaloacetate C) Citric acid D) NADH Correct Answer: B) Oxaloacetate Question 49 What type of reaction is responsible for breaking down glucose during glycolysis?

A) Hydrolysis B) Oxidation C) Reduction D) Isomerization Correct Answer: B) Oxidation Question 50 Which of the following molecules is produced during the Krebs cycle? A) Lactic acid B) Ethanol C) NADH D) Both A and C Correct Answer: C) NADH Question 51 Which process occurs in the mitochondria and uses oxygen to produce ATP? A) Glycolysis B) Krebs cycle C) Fermentation D) Photosynthesis Correct Answer: B) Krebs cycle Question 52 In the light-dependent reactions of photosynthesis, what is the primary role of water?

A) To produce glucose B) To provide electrons and protons C) To generate ATP D) To absorb sunlight Correct Answer: B) To provide electrons and protons Question 53 Which of the following best describes the function of ATP in cellular processes? A) It acts as a storage molecule for genetic information. B) It serves as a building block for nucleic acids. C) It provides energy for various cellular activities. D) It functions as an enzyme. Correct Answer: C) It provides energy for various cellular activities. Question 54 Which metabolic pathway is common to both aerobic and anaerobic respiration? A) Krebs cycle B) Glycolysis C) Electron transport chain D) Oxidative phosphorylation Correct Answer: B) Glycolysis Question 55 What is the main function of NADH in cellular respiration? A) To provide energy for ATP synthesis B) To donate electrons to the electron transport chain

C) To catalyze metabolic reactions D) To fix carbon in the Calvin cycle Correct Answer: B) To donate electrons to the electron transport chain Question 56 Which of the following is a characteristic of aerobic respiration? A) It produces less ATP compared to anaerobic respiration. B) It does not require oxygen. C) It produces carbon dioxide as a byproduct. D) It occurs only in prokaryotic cells. Correct Answer: C) It produces carbon dioxide as a byproduct. Question 57 Which process uses the energy released from electrons moving down the electron transport chain to pump protons into the intermembrane space of mitochondria? A) Chemiosmosis B) Substrate-level phosphorylation C) Photolysis D) Fermentation Correct Answer: A) Chemiosmosis Question 58 In photosynthesis, what is the source of the oxygen released as a byproduct? A) Carbon dioxide B) Water C) Glucose

D) ATP

Correct Answer: B) Water Question 59 Which compound is regenerated during the last step of the Calvin cycle? A) RuBP (Ribulose bisphosphate) B) G3P (Glyceraldehyde 3-phosphate) C) ATP D) NADPH Correct Answer: A) RuBP (Ribulose bisphosphate) Question 60 How does temperature affect enzyme activity? A) Higher temperatures always increase enzyme activity. B) Enzyme activity decreases with increasing temperature due to denaturation. C) Temperature has no effect on enzyme activity. D) Enzyme activity is maximized at very low temperatures. Correct Answer: B) Enzyme activity decreases with increasing temperature due to denaturation. Question 61 Which of the following is the primary function of the thylakoid membrane in chloroplasts? A) To produce glucose B) To conduct the light-dependent reactions of photosynthesis C) To synthesize fatty acids

D) To store starch Correct Answer: B) To conduct the light-dependent reactions of photosynthesis Question 62 What is the outcome of the transition reaction that converts pyruvate to acetyl-CoA? A) Reduction of NAD⁺ to NADH B) Production of ATP C) Release of carbon dioxide D) Both A and C Correct Answer: D) Both A and C Question 63 Which molecule serves as the primary electron donor in the light-dependent reactions of photosynthesis? A) NADH B) H₂O C) CO₂ D) Glucose Correct Answer: B) H₂O Question 64 What is the primary purpose of cellular respiration? A) To produce oxygen B) To synthesize carbohydrates C) To generate ATP from the breakdown of glucose D) To fix carbon dioxide

Correct Answer: C) To generate ATP from the breakdown of glucose Question 65 In the Krebs cycle, what is the significance of oxaloacetate? A) It is converted to ATP. B) It combines with acetyl-CoA to initiate the cycle. C) It is the final product of the cycle. D) It is produced from lactic acid. Correct Answer: B) It combines with acetyl-CoA to initiate the cycle. Question 66 Which of the following is NOT a stage of cellular respiration? A) Glycolysis B) Fermentation C) Krebs cycle D) Electron transport chain Correct Answer: B) Fermentation Question 67 What is the final product of glycolysis? A) Acetyl-CoA B) Pyruvate C) Lactic acid D) Ethanol Correct Answer: B) Pyruvate

Question 68 During which process is carbon dioxide produced? A) Glycolysis B) Krebs cycle C) Electron transport chain D) Calvin cycle Correct Answer: B) Krebs cycle Question 69 Which of the following is a product of anaerobic respiration in yeast? A) Lactic acid B) Ethanol C) Acetyl-CoA D) Glucose Correct Answer: B) Ethanol Question 70 What is the primary function of the chlorophyll pigment in photosynthesis? A) To absorb light energy B) To fix carbon dioxide C) To produce oxygen D) To synthesize glucose Correct Answer: A) To absorb light energy Question 71

What happens to the energy stored in glucose during cellular respiration? A) It is released as heat. B) It is stored as glycogen. C) It is converted into ATP. D) It is used to build proteins. Correct Answer: C) It is converted into ATP. Question 72 What role does FADH₂ play in cellular respiration? A) It acts as an electron donor in the Krebs cycle. B) It is a byproduct of glycolysis. C) It is converted to glucose. D) It is produced during fermentation. Correct Answer: A) It acts as an electron donor in the Krebs cycle. Question 73 In which cellular structure does photosynthesis take place? A) Mitochondria B) Nucleus C) Chloroplast D) Ribosome Correct Answer: C) Chloroplast Question 74 Which of the following processes occurs in the cytoplasm of the cell?

A) Krebs cycle B) Glycolysis C) Electron transport chain D) Calvin cycle Correct Answer: B) Glycolysis Question 75 What is the primary purpose of the light-independent reactions of photosynthesis? A) To capture sunlight B) To produce ATP and NADPH C) To fix carbon dioxide and produce glucose D) To generate oxygen Correct Answer: C) To fix carbon dioxide and produce glucose Question 76 Which statement about anaerobic respiration is true? A) It requires oxygen. B) It produces less ATP than aerobic respiration. C) It occurs only in plant cells. D) It does not involve glycolysis. Correct Answer: B) It produces less ATP than aerobic respiration. Question 77 During the light-dependent reactions, what is the main role of photosystems? A) To synthesize glucose B) To absorb light and transfer energy