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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Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: 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 2: 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 3: 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 4: 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 5: What is cellular respiration?

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

Flashcard 6: What is cellular respiration?

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

Flashcard 7: 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 8: 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 9: 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 10: 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 11: 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 12: 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 13: What is the immediate energy currency molecule produced in respiration?

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

Flashcard 14: Where does glycolysis occur in a eukaryotic cell?

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

Flashcard 15: 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 16: Where does the link reaction (pyruvate oxidation) occur in eukaryotes?

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

Flashcard 17: Where does the Krebs (citric acid) cycle occur in eukaryotes?

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

Flashcard 18: Where is the electron transport chain located in mitochondria?

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

Flashcard 19: 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 20: 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 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: 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 23: 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 24: 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 25: What is the final electron acceptor in aerobic respiration?

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

Flashcard 26: 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 27: 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 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 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 30: 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.