Deck 5: Aerobic Respiration and the Mitochondrion

Question 1

What is the terminal electron acceptor of the electron-transport chain in cells undergoing aerobic respiration?

A)water
B)O₂
C)CO₂
D)CO
E)glucose

Answer 1

B

Question 2

What are the two interconnected domains of the inner mitochondrial membrane?

A)inner boundary membrane, cristae
B)central boundary membrane, cristae
C)cristae boundary membrane, outer boundary membrane
D)inner boundary membrane, outer boundary membrane
E)cristae, matrix

Answer 2

A

Question 3

How is the energy used to make ATP via the electron-transport chain generated?

A)The energy from electrons bound to reduced coenzymes is used to create a steep electrochemical gradient.
B)Electrons bound to NADH are used to generate an H⁺ ion gradient across the inner mitochondrial membrane.
C)Electrons bound to FADH₂ are used to generate a proton gradient across the inner mitochondrial membrane.
D)Electrons bound to NADH are used to generate a proton gradient across the inner mitochondrial membrane.
E)All of these are correct.

Answer 3

E

Question 4

What evidence suggests that the outer mitochondrial membrane has evolved from the outer membrane that is part of the cell wall of certain bacteria?

A)the presence of porins in both membranes
B)the virtual absence of cholesterol from both membranes
C)both membranes being rich in cardiolipin d both membranes being rich in diphosphatidylglycerol

Question 5

Which of the following is regulated by mitochondria?

A)cytosolic levels of chloride ions
B)intracellular levels of K⁺ ions
C)cytosolic levels of Ca²⁺ ions
D)process of closure in endocytosis

Question 6

The inner boundary membrane is particularly rich in which of the following?

A)protons
B)transporter proteins responsible for the import of mitochondrial proteins
C)Krebs cycle enzymes
D)enzymes of the glycolytic pathway
E)glycosaminoglycans

Question 7

To what is the 2-carbon fragment of acetyl CoA added to make citric acid at the start of the Krebs cycle?

A)oxaloacetate
B)citric acid
C)succinate
D)α-ketoglutarate
E)isocitric acid

Question 8

In which two alternative ways can pyruvate and NADH be metabolized?

A)fermentation; hydrolysis of PGAL
B)condensation of PGAL; fermentation
C)aerobic processes using the Krebs cycle; fermentation
D)anaerobic processes using the Krebs cycle; fermentation
E)aerobic processes using the Krebs cycle; hydrolysis of PGAL

Question 9

Which component involved in the Krebs (TCA)cycle is bound to the inner mitochondrial membrane?

A)oxaloacetate
B)acetyl CoA
C)succinate dehydrogenase
D)succinate
E)succinyl CoA

Question 10

The presence of Ca²⁺ ion transport molecules in the inner mitochondrial membrane is consistent with the mitochondrion's role in _______.

A)muscle contraction
B)regulating cytosolic Ca²⁺ ion concentration
C)ATP production
D)ADP production
E)control of membrane fusion

Question 11

Mitochondria are sites of the __________.

A)synthesis of certain amino acids
B)synthesis of heme groups
C)uptake of Ca²⁺ ions
D)release of Ca²⁺ ions
E)all of these are correct

Question 12

What advantage do the cristae confer on the mitochondria?

A)They allow the mitochondria to shrink.
B)They greatly increase the surface area for aerobic respiration machinery.
C)They confer resiliency on the cells.
D)They allow swelling of mitochondria.
E)They activate the matrix.

Question 13

Where are most of the enzymes of the Krebs cycle located?

A)in the intercristal space
B)on the cristae
C)on the ribosomes
D)in the soluble phase of the mitochondrial matrix
E)in the intermembrane space

Question 14

How many carbons from one original glucose molecule enters the Krebs cycle in a cell in which respiration does not take place?

A)0
B)1
C)2
D)4
E)5

Question 15

Which of the following is not found in a reducing atmosphere?

A)H₂
B)NH₃
C)O₂
D)H₂O
E)Both O₂ and H₂O

Question 16

How many carbons from one original glucose molecule enters the Krebs cycle in a cell capable of respiration?

A)0
B)1
C)2
D)4
E)5

Question 17

What happens to the carbons of pyruvate that do not enter the Krebs cycle?

A)They are converted to carbohydrates.
B)They are converted to CO₂.
C)They are converted to glucose.
D)They are converted to ATP.
E)They are converted to carbon monoxide (CO).

Question 18

From what does the mitochondrial RNA polymerase appear to have evolved?

A)the multisubunit RNA polymerase found in prokaryotic cells
B)the multisubunit RNA polymerase found in eukaryotic cells
C)the multisubunit RNA polymerase found in bacterial viruses (bacteriophage)
D)the single subunit RNA polymerase found in bacterial viruses (bacteriophage)

Question 19

What is defined as a domain of the inner mitochondrial membrane that is present within the interior of the mitochondrion as a series of invaginated membranous sheets?

A)inner boundary membrane
B)outer boundary membrane
C)cristae
D)matrix
E)pseudopodia

Question 20

What molecule is responsible for conveying 2 carbons from pyruvate to the Krebs cycle?

A)Coenzyme G
B)Coenzyme A
C)Acetate
D)pyruvate
E)oxaloacetate

Question 21

On average, how many ATPs would be made if 4 NADH and 6 FADH₂ molecules donated their high-energy electrons to the mitochondrial electron-transport chain?

A)10
B)24
C)12
D)30
E)20

Question 22

Which enzyme of the Krebs (TCA)cycle is different from the others with respect to its location and where is it located?

A)succinate dehydrogenase, mitochondrial matrix
B)malate dehydrogenase, mitochondrial matrix
C)succinate dehydrogenase, inner mitochondrial membrane
D)malate dehydrogenase, inner mitochondrial membrane
E)succinate dehydrogenase, intermembrane space

Question 23

What type of electron carrier has a prosthetic group derived from vitamin B₂?

A)flavoproteins
B)cytochromes
C)copper atom containing carriers
D)ubiquinone
E)iron-sulfur proteins

Question 24

What is the final electron acceptor in the electron-transport chain of aerobic respiration?

A)water
B)carbon dioxide
C)carbon monoxide
D)hydrogen
E)oxygen

Question 25

What is unusual about the way that H⁺ ions are transported across the inner mitochondrial membrane as compared to the movement of other ions like Na⁺ and Cl^- ions?

A)Na⁺ and Cl^- ions must traverse the full distance, but H⁺ ions materialize on the other side of the membrane.
B)Na⁺ and Cl^- ions must traverse the full distance, but H⁺ ions can hop through a channel by exchanging themselves with other protons found along the pathway.
C)Na⁺ and Cl^- ions can hop through a channel by exchanging themselves with other similar ions found along the pathway, but H⁺ ions must traverse the full distance.
D)Na⁺ and Cl^- ions must traverse the full distance, but H⁺ ions must only go halfway.
E)Na⁺ and Cl^- ions must traverse the full distance, but H⁺ ions must change into neutrons first.

Question 26

Standard redox potential is measured by:

A)connecting a reference half cell to a sample half cell via a MgSO₄ salt bridge
B)detecting proton flow across the salt bridge
C)using a voltmeter to measure electron flow
D)employing a reference half cell containing a 0.1M H⁺ solution in equilibrium with H₂ gas at 1 atmosphere pressure

Question 27

How do mitochondria generate and store the energy used to produce most of the ATP made during aerobic respiration?

A)by producing heat
B)by generating a heat gradient
C)by generating a proton gradient
D)by generating a Cl^- ion gradient
E)by generating a Na⁺ ion gradient

Question 28

Of the five types of electron carriers, which has the smallest molecular mass?

A)flavoproteins
B)cytochromes
C)copper atom containing carriers
D)ubiquinone
E)iron-sulfur proteins

Question 29

Spontaneous oxidation-reduction (redox)reactions are accompanied by ________.

A)a gain of heat energy
B)a loss of free energy
C)a gain of free energy
D)a loss of heat energy
E)a gain of heat loss

Question 30

What type of electron carrier has a prosthetic group derived from riboflavin?

A)flavoproteins
B)cytochromes
C)copper atom containing carriers
D)ubiquinone
E)iron-sulfur proteins

Question 31

Why must the process by which cytochrome oxidase works be efficient?

A)If it is not, mitochondria will shrink.
B)If it is not, mitochondria will swell and burst.
C)If it is not, free radicals will be released.
D)If it is not, the mitochondria could denature.
E)All of these are correct.

Question 32

The formation of ATP by the enzymatic transfer of a phosphate group from a donor molecule to ADP is called ________.

A)substrate-level phosphorylation
B)oxidative phosphorylation
C)cyclic photophosphorylation
D)noncyclic photophosphorylation
E)indigenous phosphorylation

Question 33

How do respiratory poisons such as carbon monoxide and cyanide exert their effect?

A)They break down oxygen.
B)They bind to electrons.
C)They bind to the cytochrome oxidase catalytic site.
D)They bind to oxygen.
E)They denature the inner mitochondrial membrane.

Question 34

You are trying to figure out an electron transport pathway including the following electron transport molecules: B, K, T, Q and X. You do so by employing inhibitors for various steps in the process. When you do, you get the following results: Inhibitor Electron Transport Molecules Trapped in Reduced Form
Ticin Q & K
Digitin K
Estin T, K, Q & B
Lucin Q, K & T
What is the order of the molecules (the pathway)in the electron-transport chain suggested by the above data from the most reduced to the least reduced molecule?

A)K -> T -> B -> Q -> X
B)K -> X -> B -> Q -> T
C)K -> Q -> T -> B -> X
D)X -> B -> T -> Q -> K
E)T -> B -> K -> Q -> X

Question 35

What is the name of the process by which the electron-transport chain generates the electrochemical gradient that drives ATP production in the mitochondrion?

A)osmosis
B)diffusion
C)facilitated diffusion
D)chemiosmosis

Question 36

What is another name from for partially reduced ubiquinone?

A)ubiquinone
B)ubisemiquinone
C)ubiquinol
D)ubiquinde
E)ubiquinate

Question 37

The standard redox potential of the NADP⁺/NADPH half reaction = -0.324 V. The standard redox potential of the fumarate/succinate half reaction = +0.031 V. What is the voltage change for coupling these redox reactions and in which direction will electrons move?

A)0.355 volts; fumarate will be reduced to succinate and NADPH will be oxidized to NADP⁺
B)-0.355 volts; fumarate will be reduced to succinate and NADPH will be oxidized to NADP⁺
C)0.355 volts; succinate will be reduced to fumarate and NADP⁺ will be oxidized to NADPH
D)-0.355 volts; fumarate will be oxidized to succinate and NADPH will be reduced to NADP⁺

Question 38

Standard redox potential (E₀)for a solution is _____________________

A)considered positive if electrons flow from the sample half cell to the reference half cell
B)considered negative if electrons flow from the sample half cell to the reference half cell
C)calculated in any biochemical comparison of redox potentials between cellular cofactors and other molecules
D)measured at absolute zero (0K)

Question 39

What is formed when electrons reach the bottom of the mitochondrial electron-transport chain and bind to the final electron acceptor?

A)water
B)carbon dioxide
C)carbon monoxide
D)hydrogen
E)oxygen

Question 40

___________ exhibit lower electron affinity.

A)Strong oxidizing agents
B)Strong elucidating agents
C)Strong reducing agents
D)Weak reducing agents
E)Weak eliminating agents

Question 41

Which complex found in the electron-transport chain (ETC)consists of just four polypeptides, and which high energy electron carrier shuttles its electrons into the ETC via the complex?

A)complex I; NADH
B)complex II; NADH
C)complex III; NADH
D)complex II; FADH₂
E)complex III; FADH₂

Question 42

Of the five types of electron carriers, which has the greatest ratio of iron atoms to electrons carried?

A)flavoproteins
B)cytochromes
C)copper atom containing carriers
D)ubiquinone
E)iron-sulfur proteins

Question 43

In the Clark electrode system, oxygen levels are measured by:

A)placing metal strips of platinum and silver in an electrolyte system containing sodium bromide
B)placing metal strips of platinum and copper in an electrolyte system containing potassium chloride
C)detecting temperature changes across the electrodes induced by redox reactions
D)detecting voltage changes when redox reactions involving oxygen, two metals and chloride ions take place.

Question 44

How many catalytic sites does ATP synthase possess?

A)1
B)2
C)3
D)6
E)4

Question 45

Electrochemical gradients have both _________ and __________ component.

A)a concentration, an acidic
B)an acidic, an electrical
C)a concentration, a basic
D)a concentration, an electrical
E)an acidic, a basic

Question 46

The energy expended during the formation of ATP by ATP synthase is required to _______.

A)attach the phosphate group to ADP
B)attach the phosphate group to ATP
C)release the tightly bound ATP from the ATP synthase catalytic site
D)attach the tightly bound ATP to the ATP synthase catalytic site
E)move protons against their gradient

Question 47

Pathways in which H⁺ ions can "hop" through a channel by exchanging themselves with other protons present along the pathway are called ___________.

A)proton conduction wires
B)electrical wires
C)proton pathways
D)proton conveyer belt
E)proton conduction pathways and proton wires

Question 48

Red light is emitted at a wavelength of:

A)900nm
B)660nm
C)330 nm
D)250 nm

Question 49

Which statement regarding the Clark-type transcutaneous oxygen sensor is INCORRECT?

A)An electrode is placed on the patient's skin to allow oxygen diffusion from the bloodstream into the electrode.
B)Oxygen movement through the electrode is assisted by using a small heating element.
C)The sensor works better on adult patients than young babies.
D)The skin of adults is less permeable to oxygen.

Question 50

A pulse oximeter has all of the characteristics detailed below EXCEPT:

A)two light emitting diodes, one emitting at 660 nm and one at 900 nm
B)measurement of light transmission at two wavelengths permits evaluation of the proportion of hemoglobin molecules which are carrying oxygen
C)the oximeter can be easily attached to a finger or earlobe
D)skin thickness and pigmentation do not influence the accuracy of the data derived from the oximeter

Question 51

Of the five types of electron carriers, which has a component located outside the lipid bilayer?

A)flavoproteins
B)cytochromes
C)copper atom containing carriers
D)ubiquinone
E)iron-sulfur proteins

Question 52

Complex III of the electron-transport chain (ETC)moves electrons from______________ to further down the ETC towards the terminal electron acceptor.

A)Complex I only
B)Complex II only
C)Complex I and Complex II
D)Complex IV

Question 53

Infra-red light is emitted at a wavelength of:

A)900nm
B)660nm
C)330 nm
D)250 nm

Question 54

What percentage of blood oxygen is dissolved in the liquid plasma component?

A)0.5%
B)1%
C)2%
D)10%

Question 55

In the electrochemical gradient established in mitochondria:

A)10% of the free energy generated by the proton-motive force is derived from the voltage gradient and 90% is derived from the chemical gradient
B)80% of the free energy generated by the proton-motive force is derived from the voltage gradient and 20% is derived from the chemical gradient
C)59% of the free energy generated by the proton-motive force is derived from the voltage gradient and 41% is derived from the chemical gradient
D)65% of the free energy generated by the proton-motive force is derived from the voltage gradient and 35% is derived from the chemical gradient

Question 56

The F₀ base of ATP synthase serves as ______.

A)an enzyme that synthesizes ATP
B)an enzyme that hydrolyzes ATP
C)a channel that conducts protons from the intermembrane space back to the matrix
D)a channel that conducts protons from the matrix back to the intermembrane space
E)a proton pump

Question 57

The energy released by proton movement through ATP synthase ___________.

A)directly phosphorylates ADP to ATP
B)increases the binding affinity of the active site for the ATP product
C)directly phosphorylates ATP to ADP
D)decreases the binding affinity of the active site for the ATP product
E)directly phosphorylates AMP to ATP

Question 58

The gateway to the electron-transport chain _______________

A)catalyses the transfer of electrons from FADH₂ to ubiquinone
B)is known as FADH₂ dehydrogenase
C)catalyses the transfer of electrons from NADH to ubiquinone
D)forms ubiquinone in its redox transfer

Question 59

Why did dinitrophenol (DNP)kill patients who took the drug to help them lose weight?

A)It caused temperatures of the patients to get too high.
B)It blocked hemoglobin synthesis.
C)It caused an infection.
D)It caused total paralysis.
E)It prevented the patients from breathing.

Question 60

What is the purpose of uncoupling proteins in mammalian brown adipose tissue?

A)They give the tissue its color.
B)They help the tissue expand and contract when needed.
C)They function as a source of heat production during exposure to cold temperatures.
D)They allow the production of a larger number of ATPs per glucose.
E)They allow muscles to contract more efficiently.

Question 61

Why might large aggregates of mitochondria be located in the muscle cells of individuals with ragged red fiber disease?

A)the poorly functioning organelles proliferate in an attempt to meet cellular energy needs, just as they would for an athlete in training
B)the abnormal mitochondria are using all ATP they produce to replicate at an abnormally high rate
C)the mitochondria are excessively fragile and are damaged during biopsy, so that counting reveals an unrealistic assessment of their numbers
D)all choices are implausible

Question 62

Which of the following is true of peroxisomes?

A)Peroxisomes contain more than 50 enzymes involved in diverse activities.
B)Peroxisomes contain enzymes that oxidize very-long-chain fatty acids.
C)Peroxisomes contain the enzyme luciferase, which generates the light emitted by fireflies.
D)All of these are correct.

Question 63

Which activity below is NOT thought to be driven by the proton-motive force?

A)formation of the spindle
B)ADP and inorganic phosphate uptake into the mitochondrion in exchange for ATP and H⁺, respectively
C)uptake of Ca²⁺ ions into the mitochondrion
D)the events of mitochondrial fusion
E)uptake of specifically targeted proteins into the mitochondrion from the matrix

Question 64

From which parent are mitochondria inherited?

A)mitochondria are derived from the spermatid cytosol
B)mitochondria are derived from the egg cytoplasm
C)mitochondria are derived from both egg and sperm at the time of fertilization
D)mitochondria arise only once the zygote begins to develop independently as a diploid life form.

Question 65

Why would the individual described in Rudolf Luft's 1962 case study of mitochondrial dysfunction possibly be exercise intolerant?

A)her mitochondria produce excess ATP, making muscle contraction difficult
B)her mitochondria produce excess ADP, making muscle contraction difficult
C)her mitochondria produce little ATP, making muscle contraction difficult
D)her mitochondria produce little ADP, making muscle contraction difficult

Question 66

The L conformation of an ATP synthase catalytic site ________.

A)has a very low affinity for nucleotides
B)loosely binds AMP and an inorganic phosphate group
C)has a very low affinity for proteins
D)binds ATP, ADP and inorganic phosphate groups tightly
E)loosely binds ADP and an inorganic phosphate group

Question 67

An unusual type of phospholipid called ___________ is found in the myelin sheath that insulates brain axons; abnormalities in the synthesis of this phospholipid can lead to severe neurological dysfunction.

A)plasmins
B)sphingolipids
C)plasmalogens
D)insulins
E)luciferases

Question 68

Which of the statements below served as evidence that rotational catalysis occurs in ATP synthase?

A)movement was directly observed in the electron microscope
B)a fluorescently labeled actin filament attached to the enzyme's ɤ subunit was seen to rotate when ATP was added to the enzyme which was fixed to a cover slip
C)circular dichroism revealed the movement
D)an inhibitor stopped the enzyme movement
E)atomic force microscopy showed the movement

Question 69

If a couple had one child with ragged red fiber disease and wished to have a healthy second child, mitochondrial replacement therapy might be discussed as an option. Technically, how many parents would the child possess after such a treatment?

A)1
B)2
C)3
D)4

Question 70

Peroxisomal enzymes possess all of the characteristics listed EXCEPT:

A)produce hydrogen peroxide
B)break down hydrogen peroxide
C)include catalase
D)may sometimes be located in peroxisomes

Question 71

Which molecule below plays a key role in regulating respiratory rate in the mitochondrion?

A)ADP
B)inorganic phosphate
C)ATP
D)molecular oxygen
E)gaseous nitrogen

Question 72

In the experiment that demonstrated that rotational catalysis occurs, a fluorescently labeled actin filament attached to the ATP synthase enzyme's ɤ subunit was seen to rotate when ATP was added to the enzyme, which was fixed to a cover slip. With each step in the rotational catalysis, how much could the actin filament be seen to rotate?

A)0°
B)360°
C)120°
D)90°
E)3°

Question 73

X-linked adrenoleukodystropy is a condition with all of the following characteristics EXCEPT:

A)onset in mid-childhood
B)abnormal functioning of a mitochondrial enzyme
C)symptoms including adrenal gland failure and neurological disorders
D)defects in the transportation of very long chain fatty acids

Question 74

The three catalytic sites of ATP synthase ___________.

A)have different substrate binding affinities
B)have different product binding affinities
C)at any one time are present in different conformations
D)pass sequentially through their three different conformations
E)all of these are correct

Question 75

What drives the rotation of the F₁ head of ATP synthase?

A)proton movement from intermembrane space to the matrix
B)proton movement from the matrix to the intermembrane space
C)ATP hydrolysis
D)ATP condensation
E)proton movement from the cytoplasm to the intermembrane space

Question 76

What energy source other than ATP hydrolysis do mitochondria, unlike most other organelles, routinely use to power their activities?

A)ADP hydrolysis
B)proton-motive force
C)Na⁺ ion gradient
D)K⁺ ion gradient
E)Ca²⁺ gradient

Question 77

Mitochondrial DNA suffers a higher mutation rate than nuclear DNA by a factor of:

A)2
B)10
C)50
D)1500

Question 78

It has been shown that one part of ATP synthase rotates relative to another part of the enzyme, a phenomenon called___________.

A)turning catalysis
B)revolutionary catalysis
C)rotational catalysis
D)rotatalysis
E)revolalysis

Question 79

Which molecule below plays a key role in regulating the rate of glycolysis and Krebs cycle by regulating the activity of key enzymes?

A)ADP
B)inorganic phosphate
C)ATP
D)molecular oxygen
E)gaseous nitrogen

Question 80

What properties do mitochondria share with peroxisomes?

A)Both form by splitting from preexisting organelles, using some of the same proteins to accomplish the feat.
B)Both import preformed proteins from the cytosol.
C)Both engage in similar types of oxidative metabolism.
D)At least one enzyme is found in the mitochondria of some mammals and the peroxisomes of others.
E)All of these are correct.