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What process occurs in structure H? a. protein synthesis |
c. photosynthesis Chloroplasts are the sites of photosynthesis. |
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What molecules belong in space A and B? a. glucose and carbon dioxide |
c. glucose and oxygen Photosynthesis produces glucose and releases oxygen into the atmosphere. |
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What organelle is indicated by the letter C? a. chloroplast |
c. mitochondrion Mitochondria are the sites of cellular respiration. |
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What molecules belong in spaces E and F? a. glucose, water, carbon dioxide, and oxygen |
b. carbon dioxide and water Carbon dioxide and water are by-products of cellular respiration. |
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What process occurs in Box A? a. electron transport and oxidative phosphorylation |
b. glycolysis Glycolysis occurs in the cytosol. |
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What process occurs within Box B? a. photophosphorylation |
b. the citric acid cycle The citric acid cycle transfers electrons to NADH and FADH2. |
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What molecule is indicated by the letter D? a. glucose |
b. oxygen Oxygen is the final electron acceptor of cellular respiration. |
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Which term describes the degree to which an element attracts electrons? a. Polarity. |
c. Electronegativity. Electronegativity is the tendency of an atom to attract electrons toward itself. |
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Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other? a. Ionic and covalent. |
d. Anion and cation. Each atom will carry a charge from the transfer of electrons. |
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Which of the following statements is true of the bonds in a water molecule? a. The electron in each hydrogen atom is completely transferred to the oxygen atom, and each hydrogen atom has a net charge of +1. |
b. Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero. The oxygen and hydrogen atoms in water have partial charges, but the molecule has a net charge of zero. |
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Which of the following statements is not true of most cellular redox reactions? a. The electron acceptor is reduced. |
d. A hydrogen atom is transferred to the atom that loses an electron. A hydrogen atom (proton, or H+) is often transferred to the atom that gains an electron. |
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What kind of bond is formed when lithium and fluorine combine to form lithium fluoride? a. Redox. |
c. Ionic. The complete transfer of an electron from lithium to fluorine results in a stable compound in which both atoms have full outermost shells. |
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Gaseous hydrogen burns in the presence of oxygen to form water: 2H2 + O2 → 2H2 O + energy Which molecule is oxidized and what kind of bond is formed? a. Hydrogen, polar. |
a. Hydrogen, polar. Hydrogen loses electrons to oxygen, which is more electronegative and thus pulls the electrons closer to itself in the water molecule. |
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How many NADH are produced by glycolysis? a. 1 |
d. 2 Two NADH molecules are produced by glycolysis. |
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In glycolysis, ATP molecules are produced by _____. a. photophosphorylation |
c. substrate-level phosphorylation A phosphate group is transferred from glyceraldehyde phosphate to ADP. |
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Which of these is NOT a product of glycolysis? a. pyruvate |
b. FADH2 FADH2 is a product of the citric acid cycle. |
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In glycolysis, what starts the process of glucose oxidation? a. FADH2 |
d. ATP Some ATP energy is used to start the process of glucose oxidation. |
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In glycolysis there is a net gain of _____ ATP. a. 5 |
e. 2 It takes 2 ATP to produce 4 ATP. |
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Which of these enters the citric acid cycle? a. G3P |
c. acetyl CoA Acetyl CoA is a reactant in the citric acid cycle. |
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In the citric acid cycle, ATP molecules are produced by _____. a. cellular respiration |
b. substrate-level phosphorylation A phosphate group is transferred from GTP to ADP. |
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Which of these is NOT a product of the citric acid cycle? a. FADH2 |
b. acetyl CoA Acetyl CoA enters the citric acid cycle. |
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For each glucose that enters glycolysis, _____ acetyl CoA enter the citric acid cycle. a. 2 |
a. 2 Each glucose produces two pyruvates, each of which is converted into acetyl CoA. |
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For each glucose that enters glycolysis, _____ NADH + H+ are produced by the citric acid cycle. a. 3 to 6 |
b. 6 3 NADH + H+ are produced per each acetyl CoA that enters the citric acid cycle. |
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In cellular respiration, most ATP molecules are produced by _____. a. substrate-level phosphorylation |
b. oxidative phosphorylation This process utilizes energy released by electron transport. |
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The final electron acceptor of cellular respiration is _____. a. oxygen |
a. oxygen Oxygen is combined with electrons and hydrogen to form water. |
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During electron transport, energy from _____ is used to pump hydrogen ions into the _____. a. acetyl CoA … intermembrane space |
e. NADH and FADH2 … intermembrane space The energy released as electrons, which have been donated by NADH and FADH2, is passed along the electron transport chain and used to pump hydrogen ions into the intermembrane space. |
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Structure A is _____. a. an electron acceptor |
b. ATP synthase ATP synthase phosphorylates ADP. |
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The proximate (immediate) source of energy for oxidative phosphorylation is _____. a. NADH and FADH2 |
c. kinetic energy that is released as hydrogen ions diffuse down their concentration gradient Concentration gradients are a form of potential energy. |
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Products of pyruvate metabolism: |
lactate—>fermentation in human muscle ethanol—>fermentation in yeast and bacteria acetyl CoA—>aerobic oxidation In the presence of oxygen, human cells carry out aerobic respiration, which yields acetyl CoA. In the absence of oxygen, human cells can carry out lactic acid fermentation, which yields lactate. Yeasts and many bacteria carry out alcohol fermentation, which takes place under anaerobic conditions, and produces ethanol. |
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Reactants and products of lactic acid fermentation: |
reactants—>pyruvate and NADH products—>NAD+ and lactate When an animal engages in strenuous usage of its muscles, anaerobic conditions ensue, and pyruvate is reduced to lactate. In the process, NADH is oxidized to NAD+. This NAD+ can further oxidize glyceraldehyde-3-phosphate to produce more ATP. |
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Which molecule is metabolized in a cell to produce energy for performing work? a. Glucose |
a. Glucose Glucose is used to produce high-energy ATP in a cell. |
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True or false? The potential energy in an ATP molecule is derived mainly from its three phosphate groups. a. True |
a. True The three phosphate groups in an ATP molecule carry negative charges that strongly repel each other and give ATP a large amount of potential energy. |
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Which process is not part of the cellular respiration pathway that produces large amounts of ATP in a cell? a. Glycolysis |
b. Fermentation Fermentation is an alternate pathway used when oxygen levels are low. |
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Which step of the cellular respiration pathway can take place in the absence of oxygen? a. Glycolysis |
a. Glycolysis Glycolysis can take place in the absence of oxygen; its product, pyruvate, enters the cellular respiration pathway or undergoes fermentation depending on the availability of oxygen. |
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Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration? a. ATP |
c. Carbon dioxide All of the carbon atoms in glucose are incorporated into carbon dioxide: Two molecules are formed as pyruvate is converted to acetyl CoA, and four molecules are formed during the Krebs cycle. |
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Which of the following statements about the electron transport chain is true? a. NADH and FADH2 donate their electrons to the chain. |
a. NADH and FADH2 donate their electrons to the chain. The electrons lose energy as they move down the chain, and this energy is used to create a proton gradient that drives the synthesis of ATP. |
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Which stage of glucose metabolism produces the most ATP? a. Electron transport and chemiosmosis |
a. Electron transport and chemiosmosis Electron transport and chemiosmosis (oxidative phosphorylation) can yield around 26 molecules of ATP. |
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True or false? The reactions that generate the largest amounts of ATP during cellular respiration take place in the mitochondria. a. True |
a. True Glycolysis takes place in the cytoplasm, whereas the Krebs cycle and the electron transport chain, which generate the largest amounts of ATP during cellular respiration, take place in the mitochondria. |
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In muscle cells, fermentation produces _____. a. pyruvate |
c. lactate and NAD+ These are the products of fermentation as it occurs in muscle cells. |
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In fermentation _____ is reduced and _____ is oxidized. a. pyruvate … NADH |
a. pyruvate … NADH The pyruvate from glycolysis is reduced to either lactate or ethanol, and NADH is oxidized to NAD+. |
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