Chapter 7 (Mastering Biology)

Approximately what percentage of the ATP formed by the electron transport chain is produced by substrate-level phosphorylation? 100% 10% 2% 38% 0%

0%

Approximately what percentage of the ATP formed by the reactions of glycolysis is produced by substrate-level phosphorylation? 10% 38% 0% 100% 2%

100%

In the complete oxidation of a molecule of glucose (C6H12O6) in aerobic cellular respiration, how many molecules of ATP are produced by substrate-level phosphorylation? 2 30-32 4 8

4

Which of the following molecules donates electrons directly to the electron transport chain at the lowest energy level? ATP NAD+ FAD NADH FADH2

FADH2

donates electrons to the electron transport chain.

NADH

is the final electron acceptor of the electron transport chain.

O2 (molecular oxygen)

The oxygen atoms used to form water in the complete reactions of cellular respiration are derived from which of the following molecules? glucose (C6H12O6) pyruvate (C3H3O3-) molecular oxygen (O2) carbon dioxide (CO2)

molecular oxygen (O2)

Glycolysis results in a net production of which of the following molecules from each molecule of glucose? 2 NAD+, 2 pyruvate, and 2 ATP 4 NADH, 2 pyruvate, and 4 ATP 2 NADH, 2 pyruvate, and 2 ATP 6 CO2, 2 pyruvate, and 30 ATP 6 CO2, 2 NADH, 2 pyruvate, and 2 ATP

2 NADH, 2 pyruvate, and 2 ATP

Approximately how much more free energy is supplied to the electron transport chain by NADH than by FADH2? 8 kcal/mol 45 kcal/mol 53 kcal/mol 98 kcal/mol They both feed electrons into Q, so there is no difference in free energy

8 kcal/mol

Yeast cells grown anaerobically can obtain energy by fermentation, which results in the production of ATP and lactate. ATP, CO2, and ethanol. ATP, CO2, and lactate. ATP, CO2, and acetyl CoA. ATP, NADH, and pyruvate.

ATP, CO2, and ethanol.

is a multi-protein complex within the electron transport chain.

Complex III

Why is glycolysis described as having an energy investment phase and an energy payoff phase? Early steps consume energy from ATP and NADH, and later steps store an increased amount of energy in ATP and NADH. Early steps consume energy from ATP and NADH, and later steps store an equal amount of energy in ATP and NAD+. Early steps consume energy from ATP, and later steps store an increased amount of energy in ATP and NADH. Early steps consume energy from ATP and NADH, and later steps store an increased amount of energy in ATP. Early steps consume energy from NADH, and later steps store an increased amount of energy in ATP and NADH.

Early steps consume energy from ATP, and later steps store an increased amount of energy in ATP and NADH.

Of the following lists of electron transport compounds, which one lists them in order from the one containing electrons with the highest free energy to the one containing electrons with the lowest free energy? Note that not all electron transport compounds in the electron transport chain are listed. FMN of Complex I -- NADH -- Fe-S of Complex III -- Cyt b of Complex III -- Cyt c -- Cyt a of Complex IV -- O2 FADH2 -- Fe-S of Complex II -- Q -- Fe-S of Complex III -- Cyt c -- Cyt a of Complex IV -- O2 O2 -- Cyt a of Complex IV -- Cyt c -- Fe-S of Complex III -- Q -- Fe-S of Complex II -- FADH2 FADH2 -- Fe-S of Complex II -- Fe-S of Complex III -- Q -- Cyt a of Complex IV -- Cyt c -- O2

FADH2 -- Fe-S of Complex II -- Q -- Fe-S of Complex III -- Cyt c -- Cyt a of Complex IV -- O2

If a mitochondrion ran out of molecular oxygen (O2), predict which of the following situations would occur in its electron transport chain. FADH2 would be the main electron donor to the electron transport chain instead of NADH. H2O would be made instead of O2 at the end of the chain. Electrons would start to flow in the opposite direction, converting water into O2 and H+. Cyt a 3 prosthetic groups would remain oxidized and Cyt a would have nowhere to donate electrons. FMN prosthetic groups would remain reduced and NADH would have nowhere to donate electrons.

FMN prosthetic groups would remain reduced and NADH would have nowhere to donate electrons.

is a prosthetic group present in several components of the electron transport chain.

Fe-S

As a result of an oxidation-reduction reaction, how is the oxidizing agent changed? It loses electrons and gains potential energy. It loses electrons and loses potential energy. It gains electrons and gains potential energy. It gains electrons and loses potential energy.

It gains electrons and gains potential energy.

A glucose molecule is completely broken down to carbon dioxide and water in glycolysis and the citric acid cycle, but together these two processes yield only a few molecules of ATP. What happened to most of the energy that the cell obtains from the oxidation of glucose? It was lost as heat. It is stored in the ATP that was formed by glycolysis and the citric acid cycle. It is stored in NADH and FADH2 It is stored in the carbon dioxide and water molecules released by these processes. It is stored in pyruvate.

It is stored in NADH and FADH2

In an oxidation-reduction reaction, how is the reducing agent changed? It loses electrons and gains potential energy. It gains electrons and gains potential energy. It loses electrons and loses potential energy. It gains electrons and loses potential energy.

It loses electrons and loses potential energy.

Which of the following statements about NAD+ is true? NAD+ has more chemical energy than NADH. NAD+ is reduced to NADH during glycolysis. NAD+ is oxidized by the action of dehydrogenase enzymes. NAD+ is the source of electrons used in oxidative phosphorylation.

NAD+ is reduced to NADH during glycolysis.

Which of the following molecules donates electrons directly to the electron transport chain at the highest energy level? FADH2 NADH FAD ATP NAD+

NADH

What is the correct order of electron transport compounds from best electron donor to best electron acceptor? NADH -- Cyt c -- Fe-S of Complex I -- Q -- Fe-S of Complex III -- Cyt a of Complex IV-- O2 O2 -- Fe-S of Complex I -- NADH -- Q -- Fe-S of Complex III -- Cyt c-- Cyt a of Complex IV NADH -- Fe-S of Complex I -- Q -- Fe-S of Complex III -- Cyt c-- Cyt a of Complex IV -- O2 O2 -- Cyt a of Complex IV -- Cyt c -- Fe-S of Complex III -- Q -- Fe-S of Complex I -- NADH

NADH -- Fe-S of Complex I -- Q -- Fe-S of Complex III -- Cyt c-- Cyt a of Complex IV -- O2

is a nonprotein organic electron carrier within the electron transport chain

Q (ubiquinone)

Which of the following statements about the chemiosmotic synthesis of ATP is correct? Chemiosmotic ATP synthesis requires oxygen. The chemiosmotic synthesis of ATP requires that electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane. The chemiosmotic synthesis of ATP occurs only in eukaryotic cells because it occurs in mitochondria. The energy for production of ATP from ADP comes directly from a gradient of electrons across the inner mitochondrial membrane. Oxygen participates directly in the reaction that makes ATP from ADP and P.

The chemiosmotic synthesis of ATP requires that electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane.

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

The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle.

Which one of the following statements about the redox reactions of the electron transport chain is correct? The redox reactions of the electron transport chain are directly coupled with the synthesis of ATP. The oxidation of NADH is directly coupled to the reduction of oxygen to water. NADH gains electrons in the initial reaction of the electron transport chain. The electron transport chain takes electrons from water and gives them to oxygen. The redox reactions of the electron transport chain are directly coupled to the movement of protons across a membrane.

The redox reactions of the electron transport chain are directly coupled to the movement of protons across a membrane.

Why are carbohydrates and fats considered high-energy foods? They have many oxygen atoms. They have few nitrogen atoms. They have many carbon atoms bound together by single covalent bonds. They have a large number of electrons associated with hydrogen.

They have a large number of electrons associated with hydrogen.

Inside an active mitochondrion, most electrons follow which of the following pathways? citric acid cycle → FADH2 → electron transport chain → ATP electron transport chain → citric acid cycle → ATP → oxygen citric acid cycle → NADH → electron transport chain → oxygen NADH → oxidative phosphorylation → ATP → oxygen citric acid cycle → ATP → NADH → oxygen

citric acid cycle → NADH → electron transport chain → oxygen

Where does glycolysis occur in animal cells? mitochondrial matrix outer mitochondrial membrane inner mitochondrial membrane cytosol

cytosol

In chemiosmosis, what is the most direct source of energy that is used to convert ADP + Pi to ATP? energy released as electrons flow through the electron transport system energy released from ATP hydrolysis energy released from movement of protons down their electrochemical gradient through ATP synthase energy released from substrate-level phosphorylation

energy released from movement of protons down their electrochemical gradient through ATP synthase

Under anaerobic conditions, what carbon sources can be metabolized by yeast cells to produce ATP from ADP? lactic acid pyruvate glucose ethanol

glucose

Which of the following sequences represents the correct order in which metabolic reactions occur during the complete oxidation of glucose through aerobic respiration? glucose → pyruvate oxidation → citric acid cycle → glycolysis → electron transport chain glucose → glycolysis → pyruvate oxidation → citric acid cycle → electron transport chain glucose → pyruvate oxidation → glycolysis → electron transport chain → citric acid cycle glucose → glycolysis → citric acid cycle → pyruvate oxidation → electron transport chain glucose → citric acid cycle → glycolysis → pyruvate oxidation → electron transport chain

glucose → glycolysis → pyruvate oxidation → citric acid cycle → electron transport chain

Which of the following metabolic pathways is common to both aerobic cellular respiration and anaerobic fermentation? glycolysis chemiosmosis the oxidation of pyruvate to acetyl CoA oxidative phosphorylation the citric acid cycle

glycolysis

Which of the following metabolic pathways occur(s) in the cytosol of eukaryotic cells? oxidation of pyruvate to acetyl CoA fermentation and chemiosmosis oxidative phosphorylation glycolysis and fermentation citric acid cycle

glycolysis and fermentation

Where in mitochondria is the enzyme ATP synthase localized? outer membrane electron transport chain mitochondrial matrix inner membrane

inner membrane

Where are the proteins of the electron transport chain located in a eukaryotic cell? outer mitochondrial membrane inner mitochondrial membrane cytosol mitochondrial intermembrane space mitochondrial matrix

inner mitochondrial membrane

The complete reactions of cellular respiration in the presence of oxygen (C6H12O6 + 6 O2 →→ 6 CO2 + 6 H2O + energy) result in which of the following? oxidation of O2 and reduction of H2O oxidation of C6H12O6 and reduction of O2 reduction of C6H12O6 and oxidation of CO2 reduction of CO2 and oxidation of O2

oxidation of C6H12O6 and reduction of O2

Which of the following metabolic pathways occur(s) in mitochondria? glycolysis and oxidation of pyruvate to acetyl CoA glycolysis and fermentation oxidation of pyruvate to acetyl CoA and the citric acid cycle fermentation and chemiosmosis fermentation and oxidative phosphorylation

oxidation of pyruvate to acetyl CoA and the citric acid cycle

What is the source of the energy used to generate the proton gradient across the inner mitochondrial membrane? redox reactions in the electron transport chain splitting water to form oxygen and protons ATP hydrolysis decreasing the pH in the mitochondrial matrix

redox reactions in the electron transport chain

When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the NAD+ molecule becomes dehydrogenated. oxidized. redoxed. reduced. hydrolyzed.

reduced.

Which chemical process generates the ATP produced in glycolysis? electron transport oxidative phosphorylation chemiosmosis photophosphorylation substrate-level phosphorylation

substrate-level phosphorylation

Which chemical process generates the ATP produced in the citric acid cycle? chemiosmosis substrate-level phosphorylation oxidative phosphorylation electron transport photophosphorylation

substrate-level phosphorylation

What is the primary role of oxygen in cellular respiration? to serve as an acceptor for released carbon, forming CO2 to donate high energy electrons to the electron transport chain to serve as an acceptor for electrons and protons, forming water to donate high energy electrons to NAD+, forming NADH

to serve as an acceptor for electrons and protons, forming water

The electrons stripped from glucose in cellular respiration end up in which compound? oxygen carbon dioxide ATP water NADH

water