Chapter 9

ETC products (one glucose)

10 NAD+ 2 FAD 25 ATP (net) 12 H2O 34 H+ (about)

ETC reactants (one glucose)

10 NADH 2 FADH2 O2 (breathing)

citric acid cycle products (one glucose)

2 ATP 6 NADH 2 FADH2 4 CO2

Pyruvate Processing Outputs (per one glucose)

2 Acetyl CoA 2 NADH 2 CO2

citric acid cycle reactants (one glucose)

2 Acetyl CoA 6 NAD+ 2 FAD 2 ADP 2 Pi

Pyruvate Processing Inputs (per one glucose)

2 Pyruvate 2 NAD+ 2 CoA

glycolysis products

2 pyruvate 2 ATP 2 NADH

Carbon dioxide (CO2) is released during which of the following stages of cellular respiration? A) oxidation of pyruvate to acetyl CoA and the citric acid cycle B) the citric acid cycle and oxidative phosphorylation C) fermentation and glycolysis D) oxidative phosphorylation and fermentation E) glycolysis and the oxidation of pyruvate to acetyl CoA

A

Compare and contrast substrate-level phosphorylation and oxidative phosphorylation. What do they have in common? A) Both processes produce ATP from ADP and Pi B) None of the other statements given here are true C) Both processes produce NADPH from NADH and Pi D) Both processes occur in the matrix of the mitochondria E) Both processes occur through the action of the enzyme ATP synthase

A

Fatty acids usually have an even number of carbons in their structures. They are catabolized by a process called beta-oxidation. The end products of the metabolic pathway are acetyl groupsof acetyl-CoA molecules. These acetyl groups ________. A) directly enter the citric acid cycle B) directly enter the electron transport chain C) directly enter the energy-yielding stages of glycolysis D) are directly decarboxylated by pyruvate dehydrogenase

A

What is the term for metabolic pathways that release stored energy by breaking down complex molecules? A) catabolic pathways B) thermodynamic pathways C) fermentation pathways D) anabolic pathways E) bioenergetic pathways

A

Which high-energy molecules produced during glucose oxidation would you expect to carry the highest amount of chemical energy? A) NADH B) FADH2 C) ATP D) all are equal

A

Which statement best describes what happens during the redox reaction between NADH and Complex I of the ETC A) NADH is oxidized as a pair of electrons, which are transferred to the Complex I, and H+ is pumped into the intermembrane space B) NADH is oxidized by FAD2 which is then immediately oxidized in Complex II C) NADH is reduced as a pair of electrons are transferred to O2 which picks up 2 H+ from the matrix to produce water D) Ubiquinone receives 2 electrons from NADH and then moves through the hydrophobic interior of the ETC membrane where it is oxidized by Complex II

A

Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions? A) CO2 only B) pyruvate, ATP, and NADH C) ATP only D) ATP and NADH only E) O2 only F) NADH only G) pyruvate and ATP only

B

If pyruvate oxidation is blocked, what will happen to the levels of oxaloacetate and citric acid in the citric acid cycle shown in the accompanying figure? A) Both oxaloacetate and citric acid will decrease. B) Oxaloacetate will accumulate and citric acid will decrease. C) There will be no change in the levels of oxaloacetate and citric acid. D) Both oxaloacetate and citric acid will accumulate. E) Oxaloacetate will decrease and citric acid will accumulate.

B

What molecule is produced in the citric acid cycle as a by-product of glucose oxidation and is considered a waste product? A) NADH B) Carbon dioxide C) FADH2 D) ATP

B

What purpose does fermentation serve? A) It produces an abundance of ATP when oxygen is present. B) It regenerates NAD+ from NADH to keep glycolysis going in the absence of oxygen. C) Under aerobic conditions, it drives the formation of acetyl-CoA, which then feeds into the citric acid cycle. D) It allows for the production of NADH, which keeps the electron transport chain going.

B

Which of the following statements about cellular metabolism is false? A) Glycolysis is inhibited when cellular energy levels are abundant B) Citric Acid Cycle activity is dependent solely on availability of substrate, otherwise it is unregulated C) In the ETC, electrons decrease in energy level as they are transferred from one electron carrier to the next D) Reactions of the CAC take place in the mitochondrial matrix

B

Why are fermentation reactions important for cells? A) They produce alcohol which enhances the permeability of their mitochondrial membranes to proton translocation B) They regenerate NAD+ so that glycolysis can continue to produce some ATP C) They allow the cell to conserve oxygen for the CAC D) They generate oxygen

B

A newly developed insecticide compound steals high-energy electrons from NADH and FADH2 before they can bind to the electron transport chain. Why does it kill insects? A) The citric acid cycle cannot proceed B) Glycolysis reactions are blocked C) The ETC cannot establish a proton gradient to drive chemiosmotic production of ATP D) Fermentation pathways will be switched on, supplying insufficient ATP to maintain the insect

C

During the citric acid cycle FADH2 and NADH are produced. What purpose do these molecules serve in the electron transport chain (ETC)? A) They act as phosphate donors. B) They are not used in the ETC. C) They serve as electron donors in the ETC. D) They serve as electron acceptors in the ETC.

C

Even though plant cells photosynthesize, they still use their mitochondria for oxidation of pyruvate. This will occur in ________. A) non-photosynthesizing cells only B) cells that are storing glucose only C) all cells all the time D) photosynthetic cells in the light, while photosynthesis occurs concurrently E) photosynthesizing cells in the light and in other tissues in the dark

C

In mitochondria, exergonic redox reactions A) are the source of energy driving prokaryotic ATP synthesis. B) are directly coupled to substrate-level phosphorylation. C) provide the energy to establish the proton gradient. D) reduce carbon atoms to carbon dioxide. E) are coupled via phosphorylated intermediates to endergonic processes.

C

The ATP made during fermentation is generated by _____. A) chemiosmosis B) the electron transport chain C) substrate-level phosphorylation D) aerobic respiration E) oxidative phosphorylation

C

Which of the following correctly pairs the process with its inputs and outputs? A) Electron transport and oxidative phosphorylation-Inputs: NADH, FADH2, O2, ADP, Pi; Outputs: NAD+, FAD, H2O B) Glycolysis-Inputs: glucose, NADH, ADP, Pi; Outputs: pyruvate, NAD+, ATP C) Pyruvate processing-Inputs: pyruvate, NAD+; Outputs: acetyl CoA, NADH, CO2 D) Citric acid cycle-Inputs: pyruvate, NAD+, FAD, ADP , Pi; Outputs: CO2, NADH, FADH2, ATP

C

Following glycolysis and the citric acid cycle, but before the electron transport chain and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to CO2 with some net gain of ATP. Most of the energy from the original glucose molecule at that point in the process, however, is in the form of _____. A) acetyl CoA B) glucose C) pyruvate D) NADH

D

Glycolysis is a series of ___ reactions that occurs in the _____ of cells. A) 15; mitochondria B) 10; mitochondria C) 15; cytoplasm D) 10; cytoplasm

D

How would anaerobic conditions (when no O2O2 is present) affect the rate of electron transport and ATPATP production during oxidative phosphorylation? (Note that you should not consider the effect on ATP synthesis in glycolysis or the citric acid cycle.) A) Neither electron transport nor ATP synthesis would be affected. B) Electron transport would stop but ATP synthesis would be unaffected. C) Electron transport would be unaffected but ATP synthesis would stop. D) Both electron transport and ATP synthesis would stop.

D

In mitochondrial electron transport, what is the direct role of O2? A) to provide the driving force for the synthesis of ATP from ADP and Pi B) to oxidize NADH and FADH2 from glycolysis, acetyl CoA formation, and the citric acid cycle C) to provide the driving force for the production of a proton gradient D) to function as the final electron acceptor in the electron transport chain

D

Pyruvate, a three-carbon molecule, is processed into acetyl CoA, a two-carbon molecule. What happened to the missing carbon? A) It is lost as water vapor. B) The carbon is added to ADP to make ATP. C) It is added to NAD+. D) It is lost as carbon dioxide (CO2)

D

What does the chemiosmotic hypothesis claim? A) Water is generated using electrons taken from NADH and FADH2and transported through the electron transport chain. B) ATP is generated using phosphates taken from intermediates in the electron transport chain. C) ATP is generated using a phosphate gradient produced by glycolysis and the citric acid cycle. D) ATP is generated using a proton-motive force that is produced by the electron transport chain.

D

Which electron carrier(s) would be created by the citric acid cycle? A) ATP synthase B) Acetyl CoA C) NAD+ D) NADH and FADH2 E) ATP and ADP

D

Which statement best explains why more ATP is made per molecule of NADH than per molecule of FADH2? A) FADH2 is made only in the citric acid cycle while NADH is made in glycolysis, acetyl CoA formation, and the citric acid cycle. B) There is more NADH than FADH2 made for every glucose that enters cellular respiration. C) The H+ gradient made from electron transport using NADH is located in a different part of the mitochondrion than the H+ gradient made using FADH2. D) Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor. E) It takes more energy to make ATP from ADP and Pi using FADH2 than using NADH.

D

Why is glycolysis described as having an investment phase and a payoff phase? A) It attaches and detaches phosphate groups. B) It uses glucose and generates pyruvate. C) It shifts molecules from cytosol to mitochondrion. D) It uses stored ATP and then forms a net increase in ATP. E) It both splits molecules and assembles molecules.

D

Which of the following statements describes the results of the following reaction? C6H12O6 + 6 O2 ---> 6 CO2 + 6 H2O + energy A) O2 is reduced and CO2 is oxidized B) CO2 is reduced and O2 is oxidized C) C6H12O6 is reduced and CO2 is oxidized D) O2 is oxidized and H2O is reduced E) C6H12O6 is oxidized and O2 is reduced

E

Glycolysis reactants

Glucose 2 ATP 2 NAD+ 4 ADP 4 Pi

What is the correct sequence of events in cellular respiration?

Glycolysis, pyruvate processing, citric acid cycle, electron transport, oxidative phosphorylation

___________ is the compound that functions as the electron acceptor in glycolysis.

NAD+

The reduced form of the electron acceptor in glycolysis is __________.

NADH

When the protein gramicidin is integrated into a membrane, an H+H+ channel forms and the membrane becomes very permeable to protons (H+ ions). If gramicidin is added to an actively respiring muscle cell, how would it affect the rates of electron transport, proton pumping, and ATP synthesis in oxidative phosphorylation? Remains the same: Decreases: Increases:

Remains the same: ET rate, proton pumping rate, rate of oxygen uptake Decreases: ATP synthesis, size of proton gradient Increases: none

In glycolysis, the carbon-containing compound that functions as the electron donor is __________.

glucose

When a compound donates (loses) electrons, that compound becomes __________ . Such a compound is often referred to as an electron donor.

oxidized

Once the electron donor in glycolysis gives up its electrons, it is oxidized to a compound called ___________.

pyruvate

When a compound accepts (gains) electrons, that compound becomes ___________. Such a compound is often referred to as an electron acceptor.

reduced