Biology Flashcards: Explain Energy Release In Respiration

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This deck focuses on Explain Energy Release In Respiration, giving you a quick way to review the definitions, rules, and examples that matter most for Biology.

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Flashcard 1: Where is the electron transport chain located in mitochondria?

Answer: Inner mitochondrial membrane (cristae). Folded inner membrane provides surface area for electron transport.

Flashcard 2: What is the role of acetyl-CoA in respiration?

Answer: It donates a 2-carbon acetyl group to start the Krebs cycle. Acetyl group enters Krebs cycle to complete glucose oxidation.

Flashcard 3: What is the role of enzymes in energy release during respiration?

Answer: They catalyze small steps, controlling energy release and reducing losses. Break down large energy release into manageable steps.

Flashcard 4: What does ATP synthase do during respiration?

Answer: Synthesizes ATP from ADP and inorganic phosphate using a proton gradient. Uses proton flow to drive phosphorylation of ADP.

Flashcard 5: Which statement correctly links NADH to ATP production in mitochondria?

Answer: NADH donates electrons to the ETC, driving $H^+$ pumping and ATP synthesis. NADH electrons power proton pumping and ATP formation.

Flashcard 6: What is the main purpose of glycolysis in respiration?

Answer: To split glucose into pyruvate and produce some ATP and NADH. First stage that partially breaks down glucose for energy.

Flashcard 7: What is the definition of oxidation in the context of respiration?

Answer: Loss of electrons (often loss of hydrogen or gain of oxygen). Loss of electrons releases energy in respiration.

Flashcard 8: What is the role of NAD$^+$/NADH in respiration?

Answer: NAD$^+$ accepts electrons to form NADH, which donates electrons to the ETC. Electron carrier that shuttles electrons from substrates to ETC.

Flashcard 9: What is the definition of reduction in the context of respiration?

Answer: Gain of electrons (often gain of hydrogen or loss of oxygen). Gain of electrons stores energy in respiration.

Flashcard 10: What is the relationship between respiration and ATP hydrolysis for cell work?

Answer: Respiration makes ATP; ATP hydrolysis powers cellular processes. ATP synthesis provides energy; hydrolysis releases it for work.

Flashcard 11: What is the main purpose of glycolysis in respiration?

Answer: To split glucose into pyruvate and produce some ATP and NADH. First stage that partially breaks down glucose for energy.

Flashcard 12: What is the net ATP yield from glycolysis per glucose?

Answer: Net 2 ATP. Uses 2 ATP but produces 4 ATP, giving net gain of 2.

Flashcard 13: Where is the electron transport chain located in mitochondria?

Answer: Inner mitochondrial membrane (cristae). Folded inner membrane provides surface area for electron transport.

Flashcard 14: What is cellular respiration?

Answer: ATP-producing breakdown of organic molecules, usually using oxygen. Converts glucose into usable ATP energy through oxidation.

Flashcard 15: What are the products of one turn of the Krebs cycle per acetyl-CoA?

Answer: 3 NADH, 1 FADH$_2$, 1 ATP (or GTP), and $2CO_2$. One acetyl-CoA produces multiple electron carriers and ATP.

Flashcard 16: What happens to electrons during respiration that helps release energy?

Answer: Electrons are transferred to lower-energy acceptors in redox reactions. Energy is released as electrons move to lower energy states.

Flashcard 17: What is meant by chemical energy in glucose during respiration?

Answer: Energy stored in glucose chemical bonds, especially C–H bonds. High-energy bonds store energy that can be released during oxidation.

Flashcard 18: What is the role of FAD/FADH$_2$ in respiration?

Answer: FAD accepts electrons to form FADH$_2$, which donates electrons to the ETC. Another electron carrier that feeds electrons into ETC.

Flashcard 19: What is the final electron acceptor in aerobic respiration?

Answer: Oxygen ($O_2$). Final electron acceptor that allows ETC to continue running.

Flashcard 20: What is oxidative phosphorylation?

Answer: ATP production driven by the electron transport chain and chemiosmosis. Uses electron transport and proton gradient for ATP synthesis.

Flashcard 21: What is the role of acetyl-CoA in respiration?

Answer: It donates a 2-carbon acetyl group to start the Krebs cycle. Acetyl group enters Krebs cycle to complete glucose oxidation.

Flashcard 22: Which direction do $H^+$ ions move through ATP synthase in mitochondria?

Answer: From the intermembrane space into the matrix. Protons flow down gradient through ATP synthase channel.

Flashcard 23: Where does glycolysis occur in a eukaryotic cell?

Answer: Cytosol. First stage occurs in the cell's cytoplasm.

Flashcard 24: What is the immediate energy currency molecule produced in respiration?

Answer: ATP. Universal energy carrier that powers cellular work.

Flashcard 25: Which membrane is relatively impermeable to $H^+$, enabling chemiosmosis?

Answer: Inner mitochondrial membrane. Barrier prevents proton leakage, maintaining gradient.

Flashcard 26: What happens to the ETC and ATP production if oxygen is absent?

Answer: ETC stops; oxidative phosphorylation stops; ATP yield drops sharply. No oxygen means electron transport and chemiosmosis stop.

Flashcard 27: What is formed when oxygen accepts electrons and protons at the end of the ETC?

Answer: Water ($H_2O$). Oxygen accepts electrons and combines with protons.

Flashcard 28: What is chemiosmosis in mitochondria?

Answer: ATP synthesis powered by $H^+$ flow down an electrochemical gradient. Proton gradient drives ATP synthesis through ATP synthase.

Flashcard 29: What is the approximate total ATP yield per glucose in many textbooks?

Answer: About $36$ to $38$ ATP per glucose (varies by cell type). Theoretical maximum varies based on transport efficiency.

Flashcard 30: What is oxidative phosphorylation?

Answer: ATP production driven by the electron transport chain and chemiosmosis. Uses electron transport and proton gradient for ATP synthesis.

Flashcard 31: Where does glycolysis occur in a eukaryotic cell?

Answer: Cytosol. First stage occurs in the cell's cytoplasm.

Flashcard 32: What is formed when oxygen accepts electrons and protons at the end of the ETC?

Answer: Water ($H_2O$). Oxygen accepts electrons and combines with protons.

Flashcard 33: What is the main purpose of the Krebs cycle in respiration?

Answer: To generate NADH and FADH$_2$ and release $CO_2$. Completes glucose oxidation and produces electron carriers.

Flashcard 34: What is meant by chemical energy in glucose during respiration?

Answer: Energy stored in glucose chemical bonds, especially C–H bonds. High-energy bonds store energy that can be released during oxidation.

Flashcard 35: What is the immediate energy currency molecule produced in respiration?

Answer: ATP. Universal energy carrier that powers cellular work.

Flashcard 36: Where does the Krebs (citric acid) cycle occur in eukaryotes?

Answer: Mitochondrial matrix. Acetyl-CoA is processed in the mitochondrial matrix.

Flashcard 37: What is the function of the electron transport chain (ETC) in respiration?

Answer: Transfers electrons and pumps $H^+$ to build a proton gradient. Creates proton gradient that drives ATP synthesis.

Flashcard 38: Which molecule is oxidized during aerobic respiration of glucose?

Answer: Glucose is oxidized to carbon dioxide. Glucose loses electrons and hydrogen to become $CO_2$.

Flashcard 39: Which molecule is reduced during aerobic respiration?

Answer: Oxygen is reduced to water. Oxygen gains electrons to form water at the end of the ETC.

Flashcard 40: Where does the link reaction (pyruvate oxidation) occur in eukaryotes?

Answer: Mitochondrial matrix. Pyruvate is oxidized inside the mitochondrial matrix.

Flashcard 41: Which direction do $H^+$ ions move through ATP synthase in mitochondria?

Answer: From the intermembrane space into the matrix. Protons flow down gradient through ATP synthase channel.

Flashcard 42: What is the role of enzymes in energy release during respiration?

Answer: They catalyze small steps, controlling energy release and reducing losses. Break down large energy release into manageable steps.

Flashcard 43: What is the proton motive force in mitochondria?

Answer: Potential energy stored in the $H^+$ electrochemical gradient. Gradient provides energy to drive ATP synthesis.

Flashcard 44: What is the ATP yield per glucose in fermentation (anaerobic) conditions?

Answer: 2 ATP per glucose (from glycolysis only). Only glycolysis can produce ATP without oxygen.

Flashcard 45: What is the overall word equation for aerobic respiration?

Answer: glucose + oxygen → carbon dioxide + water (+ ATP). Glucose + oxygen react to produce ATP, carbon dioxide, and water.

Flashcard 46: Which process regenerates NAD$^+$ when oxygen is unavailable?

Answer: Fermentation (lactate or ethanol pathways). Recycles electron carriers when oxygen is unavailable.

Flashcard 47: What is the overall word equation for aerobic respiration?

Answer: glucose + oxygen → carbon dioxide + water (+ ATP). Glucose + oxygen react to produce ATP, carbon dioxide, and water.

Flashcard 48: What is produced when pyruvate is oxidized to acetyl-CoA?

Answer: Acetyl-CoA, $CO_2$, and NADH. Pyruvate loses carbon as $CO_2$ and forms acetyl-CoA.

Flashcard 49: Which statement correctly links NADH to ATP production in mitochondria?

Answer: NADH donates electrons to the ETC, driving $H^+$ pumping and ATP synthesis. NADH electrons power proton pumping and ATP formation.

Flashcard 50: Which stage of respiration produces the most ATP in aerobic conditions?

Answer: Oxidative phosphorylation (ETC and chemiosmosis). Electron transport produces most ATP through chemiosmosis.

Flashcard 51: Which molecule is reduced during aerobic respiration?

Answer: Oxygen is reduced to water. Oxygen gains electrons to form water at the end of the ETC.

Flashcard 52: Which process regenerates NAD$^+$ when oxygen is unavailable?

Answer: Fermentation (lactate or ethanol pathways). Recycles electron carriers when oxygen is unavailable.

Flashcard 53: What is the approximate total ATP yield per glucose in many textbooks?

Answer: About $36$ to $38$ ATP per glucose (varies by cell type). Theoretical maximum varies based on transport efficiency.

Flashcard 54: What is the definition of reduction in the context of respiration?

Answer: Gain of electrons (often gain of hydrogen or loss of oxygen). Gain of electrons stores energy in respiration.

Flashcard 55: Which choice best describes how energy release is controlled in respiration?

Answer: Energy is released in many enzyme-catalyzed steps rather than one burst. Enzymes prevent uncontrolled energy release and heat loss.

Flashcard 56: What is the definition of oxidation in the context of respiration?

Answer: Loss of electrons (often loss of hydrogen or gain of oxygen). Loss of electrons releases energy in respiration.

Flashcard 57: Which stage of respiration produces the most ATP in aerobic conditions?

Answer: Oxidative phosphorylation (ETC and chemiosmosis). Electron transport produces most ATP through chemiosmosis.

Flashcard 58: What happens to the ETC and ATP production if oxygen is absent?

Answer: ETC stops; oxidative phosphorylation stops; ATP yield drops sharply. No oxygen means electron transport and chemiosmosis stop.

Flashcard 59: What is the relationship between respiration and ATP hydrolysis for cell work?

Answer: Respiration makes ATP; ATP hydrolysis powers cellular processes. ATP synthesis provides energy; hydrolysis releases it for work.

Flashcard 60: What is the final electron acceptor in aerobic respiration?

Answer: Oxygen ($O_2$). Final electron acceptor that allows ETC to continue running.

Flashcard 61: What is the net ATP yield from glycolysis per glucose?

Answer: Net 2 ATP. Uses 2 ATP but produces 4 ATP, giving net gain of 2.

Flashcard 62: What is the role of FAD/FADH$_2$ in respiration?

Answer: FAD accepts electrons to form FADH$_2$, which donates electrons to the ETC. Another electron carrier that feeds electrons into ETC.

Flashcard 63: Where does the link reaction (pyruvate oxidation) occur in eukaryotes?

Answer: Mitochondrial matrix. Pyruvate is oxidized inside the mitochondrial matrix.

Flashcard 64: What is the immediate source of energy used by ATP synthase to make ATP?

Answer: Energy from $H^+$ flow down the proton gradient. Proton gradient provides mechanical energy for ATP synthesis.

Flashcard 65: What is the main purpose of the Krebs cycle in respiration?

Answer: To generate NADH and FADH$_2$ and release $CO_2$. Completes glucose oxidation and produces electron carriers.

Flashcard 66: What is the role of NAD$^+$/NADH in respiration?

Answer: NAD$^+$ accepts electrons to form NADH, which donates electrons to the ETC. Electron carrier that shuttles electrons from substrates to ETC.

Flashcard 67: What is fermentation in relation to respiration?

Answer: Anaerobic pathway that regenerates NAD$^+$ so glycolysis can continue. Allows glycolysis to continue without oxygen present.

Flashcard 68: Which choice best describes how energy release is controlled in respiration?

Answer: Energy is released in many enzyme-catalyzed steps rather than one burst. Enzymes prevent uncontrolled energy release and heat loss.

Flashcard 69: What does ATP synthase do during respiration?

Answer: Synthesizes ATP from ADP and inorganic phosphate using a proton gradient. Uses proton flow to drive phosphorylation of ADP.

Flashcard 70: Which statement best explains why oxygen increases ATP yield in respiration?

Answer: It allows the ETC to run by accepting electrons at the end. Without oxygen, electron transport chain cannot function.

Flashcard 71: What happens to electrons during respiration that helps release energy?

Answer: Electrons are transferred to lower-energy acceptors in redox reactions. Energy is released as electrons move to lower energy states.

Flashcard 72: Which reduced coenzymes carry high-energy electrons to the electron transport chain?

Answer: NADH and FADH$_2$. Electron carriers transport high-energy electrons for ATP production.

Flashcard 73: Where does the Krebs (citric acid) cycle occur in eukaryotes?

Answer: Mitochondrial matrix. Acetyl-CoA is processed in the mitochondrial matrix.

Flashcard 74: Which stage of respiration directly releases carbon dioxide in eukaryotes?

Answer: Link reaction and Krebs cycle. Decarboxylation reactions remove carbon as $CO_2$.

Flashcard 75: What is fermentation in relation to respiration?

Answer: Anaerobic pathway that regenerates NAD$^+$ so glycolysis can continue. Allows glycolysis to continue without oxygen present.

Flashcard 76: What is the ATP yield per glucose in fermentation (anaerobic) conditions?

Answer: 2 ATP per glucose (from glycolysis only). Only glycolysis can produce ATP without oxygen.

Flashcard 77: Why does respiration release energy rather than requiring energy overall?

Answer: Products have lower chemical potential energy than reactants. Energy flows from high-energy glucose to lower-energy products.

Flashcard 78: What is the balanced chemical equation for aerobic respiration of glucose?

Answer: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O$ (+ ATP). Balanced equation showing 6 $O_2$ needed for complete glucose oxidation.

Flashcard 79: Identify the correct order of major stages in aerobic respiration.

Answer: Glycolysis → link reaction → Krebs cycle → ETC/chemiosmosis. Sequential stages completely oxidize glucose to $CO_2$.

Flashcard 80: Which molecule is oxidized during aerobic respiration of glucose?

Answer: Glucose is oxidized to carbon dioxide. Glucose loses electrons and hydrogen to become $CO_2$.

Flashcard 81: What is substrate-level phosphorylation?

Answer: ATP formation by direct phosphate transfer from a substrate to ADP. Direct phosphate transfer without electron transport chain.

Flashcard 82: Which stage of respiration directly releases carbon dioxide in eukaryotes?

Answer: Link reaction and Krebs cycle. Decarboxylation reactions remove carbon as $CO_2$.

Flashcard 83: What is substrate-level phosphorylation?

Answer: ATP formation by direct phosphate transfer from a substrate to ADP. Direct phosphate transfer without electron transport chain.

Flashcard 84: What is produced when pyruvate is oxidized to acetyl-CoA?

Answer: Acetyl-CoA, $CO_2$, and NADH. Pyruvate loses carbon as $CO_2$ and forms acetyl-CoA.

Flashcard 85: Which membrane is relatively impermeable to $H^+$, enabling chemiosmosis?

Answer: Inner mitochondrial membrane. Barrier prevents proton leakage, maintaining gradient.

Flashcard 86: What are the end products of glycolysis per glucose molecule?

Answer: 2 pyruvate, 2 NADH, and net 2 ATP. One glucose produces two pyruvate molecules and energy carriers.

Flashcard 87: What is the proton motive force in mitochondria?

Answer: Potential energy stored in the $H^+$ electrochemical gradient. Gradient provides energy to drive ATP synthesis.

Flashcard 88: Identify the correct order of major stages in aerobic respiration.

Answer: Glycolysis → link reaction → Krebs cycle → ETC/chemiosmosis. Sequential stages completely oxidize glucose to $CO_2$.

Flashcard 89: What are the products of one turn of the Krebs cycle per acetyl-CoA?

Answer: 3 NADH, 1 FADH$_2$, 1 ATP (or GTP), and $2CO_2$. One acetyl-CoA produces multiple electron carriers and ATP.

Flashcard 90: What is the balanced chemical equation for aerobic respiration of glucose?

Answer: $C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O$ (+ ATP). Balanced equation showing 6 $O_2$ needed for complete glucose oxidation.

Flashcard 91: What is meant by respiration being exothermic?

Answer: It releases energy, with some lost as heat. Chemical energy is converted to heat and ATP energy.

Flashcard 92: What is chemiosmosis in mitochondria?

Answer: ATP synthesis powered by $H^+$ flow down an electrochemical gradient. Proton gradient drives ATP synthesis through ATP synthase.

Flashcard 93: What is cellular respiration?

Answer: ATP-producing breakdown of organic molecules, usually using oxygen. Converts glucose into usable ATP energy through oxidation.

Flashcard 94: Why does respiration release energy rather than requiring energy overall?

Answer: Products have lower chemical potential energy than reactants. Energy flows from high-energy glucose to lower-energy products.

Flashcard 95: What is the function of the electron transport chain (ETC) in respiration?

Answer: Transfers electrons and pumps $H^+$ to build a proton gradient. Creates proton gradient that drives ATP synthesis.