Mastering Biology Chapter 9 Pre-Lecture Assignment 1

For each glucose that enters glycolysis, _____ acetyl CoA enter the citric acid cycle. a. 2 b. 4 c. 0 d. 5 e. 1

a. 2 Each glucose produces two pyruvates, each of which is converted into acetyl CoA.

In the citric acid cycle, ATP molecules are produced by _____. a. cellular respiration b. substrate-level phosphorylation c. oxidative phosphorylation d. photophosphorylation e. photosynthesis

b. substrate-level phosphorylation A phosphate group is transferred from GTP to ADP.

What molecules belong in spaces E and F? a. glucose, water, carbon dioxide, and oxygen b. carbon dioxide and water c. glucose and oxygen d. oxygen and water e. carbon dioxide and oxygen

b. carbon dioxide and water Carbon dioxide and water are by-products of cellular respiration.

Which stage of glucose metabolism produces the most ATP? a. Electron transport and chemiosmosis b. Fermentation of pyruvate to lactate c. Krebs cycle d. Glycolysis

a. Electron transport and chemiosmosis Electron transport and chemiosmosis (oxidative phosphorylation) can yield around 26 molecules of ATP.

The final electron acceptor of cellular respiration is _____. a. oxygen b. FADH2 c. CO2 d. water e. NADH

a. oxygen Oxygen is combined with electrons and hydrogen to form water.

Which molecule is metabolized in a cell to produce energy for performing work? a. Glucose b. Phosphate c. ATP d. ADP

a. Glucose Glucose is used to produce high-energy ATP in a cell.

Which step of the cellular respiration pathway can take place in the absence of oxygen? a. Glycolysis b. Krebs cycle c. Electron transport chain d. Fermentation

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.

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. b. Hydrogen, nonpolar. c. Oxygen, nonpolar. d. Oxygen, 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.

Which of the following statements about the electron transport chain is true? a. NADH and FADH2 donate their electrons to the chain. b. Electrons gain energy as they move down the chain. c. Water is the last electron acceptor. d. The electron transport chain is the first step in cellular respiration.

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.

True or false? The reactions that generate the largest amounts of ATP during cellular respiration take place in the mitochondria. a. True b. False

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.

True or false? The potential energy in an ATP molecule is derived mainly from its three phosphate groups. a. True b. False

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.

In fermentation _____ is reduced and _____ is oxidized. a. pyruvate ... NADH b. NADH ... lactate c. lactate ... ethanol d. NAD+ ... pyruvate e. lactate ... NADH

a. pyruvate ... NADH The pyruvate from glycolysis is reduced to either lactate or ethanol, and NADH is oxidized to NAD+.

For each glucose that enters glycolysis, _____ NADH + H+ are produced by the citric acid cycle. a. 3 to 6 b. 6 c. 2 d. 3 e. 0

b. 6 3 NADH + H+ are produced per each acetyl CoA that enters the citric acid cycle.

Structure A is _____. a. an electron acceptor b. ATP synthase c. an electron donor d. sensory protein e. phospholipid

b. ATP synthase ATP synthase phosphorylates ADP.

Which of these is NOT a product of glycolysis? a. pyruvate b. FADH2 c. NADH d. ATP

b. FADH2 FADH2 is a product of the citric acid cycle.

Which process is not part of the cellular respiration pathway that produces large amounts of ATP in a cell? a. Glycolysis b. Fermentation c. Krebs cycle d. Electron transport chain

b. Fermentation Fermentation is an alternate pathway used when oxygen levels are low.

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. c. Oxygen acts as the electron acceptor and is oxidized. d. There is equal sharing of the electrons between the oxygen atom and the two hydrogen atoms, and the net charge is zero.

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.

Which of these is NOT a product of the citric acid cycle? a. FADH2 b. acetyl CoA c. ATP d. NADH + H+ e. CO2

b. acetyl CoA Acetyl CoA enters the citric acid cycle.

Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration? a. ATP b. Water c. Carbon dioxide d. NADH

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.

Which term describes the degree to which an element attracts electrons? a. Polarity. b. Oxidation. c. Electronegativity. d. Reduction.

c. Electronegativity. Electronegativity is the tendency of an atom to attract electrons toward itself.

What kind of bond is formed when lithium and fluorine combine to form lithium fluoride? a. Redox. b. Nonpolar covalent. c. Ionic. d. Polar covalent.

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.

Which of these enters the citric acid cycle? a. G3P b. pyruvate c. acetyl CoA d. glucose e. NADH + H+

c. acetyl CoA Acetyl CoA is a reactant in the citric acid cycle.

What molecules belong in space A and B? a. glucose and carbon dioxide b. carbon dioxide and water c. glucose and oxygen d. oxygen and water e. carbon dioxide and oxygen

c. glucose and oxygen Photosynthesis produces glucose and releases oxygen into the atmosphere.

The proximate (immediate) source of energy for oxidative phosphorylation is _____. a. NADH and FADH2 b. ATP c. kinetic energy that is released as hydrogen ions diffuse down their concentration gradient d. substrate-level phosphorylation e. ATP synthase

c. kinetic energy that is released as hydrogen ions diffuse down their concentration gradient Concentration gradients are a form of potential energy.

In muscle cells, fermentation produces _____. a. pyruvate b. carbon dioxide, ethanol, and NAD+ c. lactate and NAD+ d. lactate, NADH, and ATP e. carbon dioxide, ethanol, NADH, and ATP

c. lactate and NAD+ These are the products of fermentation as it occurs in muscle cells.

What organelle is indicated by the letter C? a. chloroplast b. lysosome c. mitochondrion d. Golgi apparatus e. peroxisome

c. mitochondrion Mitochondria are the sites of cellular respiration.

What process occurs in structure H? a. protein synthesis b. ribosome synthesis c. photosynthesis d. intracellular digestion e. cellular respiration

c. photosynthesis Chloroplasts are the sites of photosynthesis.

During electron transport, energy from _____ is used to pump hydrogen ions into the _____. a. acetyl CoA ... intermembrane space b. NADH ... intermembrane space c. NADH and FADH2 ... mitochondrial matrix d. NADH ... mitochondrial matrix e. NADH and FADH2 ... 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.

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.

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.

What process occurs in Box A? a. electron transport and oxidative phosphorylation b. glycolysis c. the citric acid cycle d. oxidative phosphorylation e. electron transport

b. glycolysis Glycolysis occurs in the cytosol.

In cellular respiration, most ATP molecules are produced by _____. a. substrate-level phosphorylation b. oxidative phosphorylation c. cellular respiration d. photosynthesis e. photophosphorylation

b. oxidative phosphorylation This process utilizes energy released by electron transport.

What molecule is indicated by the letter D? a. glucose b. oxygen c. ATP d. pyruvate e. water

b. oxygen Oxygen is the final electron acceptor of cellular respiration.

What process occurs within Box B? a. photophosphorylation b. the citric acid cycle c. electron transport d. glycolysis e. oxidative phosphorylation

b. the citric acid cycle The citric acid cycle transfers electrons to NADH and FADH2.

In glycolysis, ATP molecules are produced by _____. a. photophosphorylation b. photosynthesis c. substrate-level phosphorylation d. oxidative phosphorylation e. cellular respiration

c. substrate-level phosphorylation A phosphate group is transferred from glyceraldehyde phosphate to ADP.

How many NADH are produced by glycolysis? a. 1 b. 3 c. 4 d. 2 e. 5

d. 2 Two NADH molecules are produced by glycolysis.

Which of the following statements is not true of most cellular redox reactions? a. The electron acceptor is reduced. b. Changes in potential energy can be released as heat. c. The reactant that is oxidized loses electrons. d. A hydrogen atom is transferred to the atom that loses an electron.

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.

In glycolysis, what starts the process of glucose oxidation? a. FADH2 b. NADPH c. ADP d. ATP e. hexokinase

d. ATP Some ATP energy is used to start the process of glucose oxidation.

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. b. Polar and nonpolar. c. Proton and electron. d. Anion and cation.

d. Anion and cation. Each atom will carry a charge from the transfer of electrons.

In glycolysis there is a net gain of _____ ATP. a. 5 b. 1 c. 3 d. 4 e. 2

e. 2 It takes 2 ATP to produce 4 ATP.