CELLULAR RESPIRATION : HARVESTING CHEMICAL ENERGY QUESTIONS AND ANSWERS GRADED A+ 2025/2026

CELLULAR RESPIRATION : HARVESTING CHEMICAL ENERGY QUESTIONS AND ANSWERS GRADED A+ 2025/2026 Multiple Choice Questions 1) What is the term for metabolic pathways that release stored energy by breaking down complex molecules? A) anabolic pathways B) catabolic pathways C) fermentation pathways D) thermodynamic pathways E) bioenergetic pathways Answer: B 2) The molecule that functions as the reducing agent (electron donor) in a redox or oxidation reduction reaction A) gains electrons and gains energy. B) loses electrons and loses energy. C) gains electrons and loses energy. D) loses electrons and gains energy. E) neither gains nor loses electrons, but gains or loses energy. Answer: B 3) When electrons move closer to a more electronegative atom, what happens? A) Energy is released. B) Energy is consumed. C) The more electronegative atom is reduced. D) The more electronegative atom is oxidized. E) A and C are correct. Answer: E 4) Why does the oxidation of organic compounds by molecular oxygen to produce CO 2 and water release free energy? A) The covalent bonds in organic molecules are higher energy bonds than those in water and carbon dioxide. B) Electrons are being moved from atoms that have a lower affinity for electrons (such as C) to atoms with a higher affinity for electrons (such as O). C) The oxidation of organic compounds can be used to make ATP. D) The electrons have a higher potential energy when associated with water and CO 2 than they do in organic compounds. E) The covalent bond in O2 is unstable and easily broken by electrons from organic molecules. Answer: B 5) Which of the following statements describes the results of this reaction? C6H12O6 6 O2 → 6 CO2 6 H2O Energy A) C6H12O6 is oxidized and O2 is reduced. B) O2 is oxidized and H2O is reduced. C) CO2 is reduced and O2 is oxidized. D) C6H12O6 is reduced and CO2 is oxidized. E) O2 is reduced and CO2 is oxidized. Answer: A 6) When a glucose molecule loses a hydrogen atom as the result of an oxidation reduction reaction, the molecule becomes A) dehydrogenated. B) hydrogenated. C) oxidized. D) reduced. E) an oxidizing agent. Answer: C 7) When a molecule of NAD (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a hydrogen ion) the molecule becomes A) hydrogenated. B) oxidized. C) reduced. D) redoxed. 8) a reducing agent.Which of the following statements describes NAD ? A) NAD is reduced to NADH during both glycolysis and the citric acid cycle. B) NAD has more chemical energy than NADH. C) NAD is reduced by the action of hydrogenases. D) NAD can donate electrons for use in oxidative phosphorylation. E) In the absence of NAD , glycolysis can still function. Answer: A 9) Where does glycolysis takes place? A) mitochondrial matrix B) mitochondrial outer membrane C) mitochondrial inner membrane D) mitochondrial intermembrane space E) cytosol Answer: E 10) The ATP made during glycolysis is generated by A) substrate level phosphorylation. B) electron transport. C) photophosphorylation. D) chemiosmosis. E) oxidation of NADH to NAD . Answer: A