Mastering Biology Chapter 9

Most CO2 from catabolism is released during A) the citric acid cycle. B) oxidative phosphorylation. C) glycolysis. D) electron transport. E) lactate fermentation

A)

In glycolysis, ATP molecules are produced by _____. A) substrate-level phosphorylation B) photosynthesis C) cellular respiration D) photophosphorylation E) oxidative phosphorylation

A); A phosphate group is transferred from glyceraldehyde phosphate to ADP

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); 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

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) Oxygen, polar. C) Oxygen, nonpolar. D) Hydrogen, nonpolar

A); 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 best describes the main purpose of the combined processes of glycolysis and cellular respiration? A) transforming the energy in glucose and related molecules in a chemical form that cells can use for work B) producing complex molecules from chemical building blocks C) catabolism of sugars and related compounds D) the breakdown of glucose to carbon dioxide and water E) breaking down ATP, so that ADP and P can be reused

A); The energy made available during cellular respiration is coupled to a production of ATP, the basic energy currency that cells use for work

In fermentation _____ is reduced and _____ is oxidized. A) pyruvate ... NADH B) lactate ... NADH C) NADH ... lactate D) NAD+ ... pyruvate E) lactate ... ethanol

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

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

A); 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.

How many NADH are produced by glycolysis? A) 3 B) 2 C) 4 D) 5 E) 1

B)

What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ → Lactate + NAD+ A) oxygen B) pyruvate C) NADH D) lactate E) NAD+

B)

Which of the following describes the process of glycolysis? A) It converts one glucose molecule to two molecules of pyruvate and carbon dioxide. B) It represents the first stage in the chemical oxidation of glucose by a cell. C) Glycolysis occurs in the mitochondria. D) Glycolysis produces 30 ATP from each molecule of glucose. E) It requires ATP and NADH

B); Catabolism of glucose begins with glycolysis

Which of these is NOT a product of glycolysis? A) NADH B) FADH2 C) pyruvate D) ATP

B); FADH2 is a product of the citric acid cycle

In glycolysis there is a net gain of _____ ATP. A) 3 B) 2 C) 5 D) 4 E) 1

B); It takes 2 ATP to produce 4 ATP

Which of the following statements is true of the bonds in a water molecule? A) Oxygen acts as the electron acceptor and is oxidized. B) Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero. C) The electron in each hydrogen atom is completely transferred to the oxygen atom, and each hydrogen atom has a net charge of +1. D) There is equal sharing of the electrons between the oxygen atom and the two hydrogen atoms, and the net charge is zero.

B); The oxygen and hydrogen atoms in water have partial charges, but the molecule has a net charge of zero

In muscle cells, fermentation produces _____. A) carbon dioxide, ethanol, NADH, and ATP B) pyruvate C) lactate and NAD+ D) carbon dioxide, ethanol, and NAD+ E) lactate, NADH, and ATP

C)

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

C); A hydrogen atom (proton, or H+) is often transferred to the atom that gains an electron

Which term describes the degree to which an element attracts electrons? A) Oxidation. B) Reduction. C) Electronegativity. D) Polarity.

C); Electronegativity is the tendency of an atom to attract electrons toward itself

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

C); 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.

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs? A) NAD+ is oxidized. B) ATP synthase pumps protons by active transport. C) The cytochromes phosphorylate ADP to form ATP. D) The pH of the matrix increases. E) The electrons gain free energy.

D)

Which statement about the citric acid cycle is correct? A) The citric acid cycle depends on the availability of NAD+, which is a product of glycolysis. B) The oxidation of compounds by the citric acid cycle requires molecular oxygen. C) The citric acid cycle produces most of the ATP that is subsequently used by the electron transport chain. D) The citric acid cycle oxidizes glucose to carbon dioxide. E) The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle.

D)

Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration? A) Water B) ATP C) NADH D) Carbon dioxide

D); 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 terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other? A) Proton and electron. B) Ionic and covalent. C) Polar and nonpolar. D) Anion and cation.

D); Each atom will carry a charge from the transfer of electrons

Which stage of glucose metabolism produces the most ATP? A) Krebs cycle B) Glycolysis C) Fermentation of pyruvate to lactate D) Electron transport and chemiosmosis

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

Which process is not part of the cellular respiration pathway that produces large amounts of ATP in a cell? A) Electron transport chain B) Glycolysis C) Krebs cycle D) Fermentation

D); Fermentation is an alternate pathway used when oxygen levels are low

Which molecule is metabolized in a cell to produce energy for performing work? A) ADP B) Phosphate C) ATP D) Glucose

D); 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) Krebs cycle B) Fermentation C) Electron transport chain D) Glycolysis

D); 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.

What kind of bond is formed when lithium and fluorine combine to form lithium fluoride? A) Nonpolar covalent. B) Redox. C) Polar covalent. D) Ionic.

D); The complete transfer of an electron from lithium to fluorine results in a stable compound in which both atoms have full outermost shells.

In glycolysis, what starts the process of glucose oxidation? A) ADP B) FADH2 C) hexokinase D) NADPH E) ATP

E); Some ATP energy is used to start the process of glucose oxidation