Deck 14: Respiration, Lithotrophy, and Photolysis

Question 1

Which of the following can be used to measure $\Delta$ pH?

A) lipid-soluble cations
B) membrane-permeant weak acids
C) oxidoreductases
D) cytochromes
E) electron acceptors

Answer 1

membrane-permeant weak acids

Question 2

Enzymes transferring electrons at the start of the ETS are referred to as __________, whereas enzymes transferring electrons to the terminal electron acceptor are designated __________.

A) dehydrogenases; oxidases
B) oxidases; dehydrogenases
C) sulfatases; nitrogenases
D) none of the above
E) all of the above

Answer 2

A

Question 3

In cytochromes, the heme group plays a key role in acquiring and transferring electrons with a(n) __________ transition.

A) Mg⁰/Mg²⁺
B) S⁰/S^2-
C) Cu⁺/C²⁺
D) Fe²⁺/Fe³⁺
E) none of the above

Answer 3

D

Question 4

Which of the following is NOT a redox pair?

A) fumarate/succinate
B) NADH/NAD⁺,
C) H₂S/H₂O
D) quinone/quinol (Q/QH₂)
E) FAD/FADH₂

Question 5

Which of the following are components of reaction centers in the electron transport system?

A) heme groups and flavin mononucleotide
B) [2Fe-2S] and [4Fe-4S] iron-sulfur clusters
C) conjugated double bonds and heteroaromatic rings
D) all of the above
E) none of the above

Question 6

What membrane system are electron transport systems embedded in?

A) mitochondrial inner membrane
B) thylakoids
C) the inner membrane of Gram-negative bacteria
D) all of the above
E) none of the above

Question 7

Some pathogenic bacteria use __________ to expel antibiotics from the cell.

A) proton-driven efflux pumps
B) sugar or amino acid inward carriers
C) heme cofactors
D) all of the above
E) none of the above

Question 8

What is lithotrophy?

A) breakdown of molecules using light energy
B) oxidation of organic electron donors to CO₂ and H₂O
C) photolysis of H₂S or H₂O coupled to CO₂ fixation
D) oxidation of inorganic electron donors such as Fe²⁺ using O₂ or anaerobic electronic acceptors
E) none of the above

Question 9

Reduction potential is defined as:

A) the tendency for a molecule to release H⁺ in solution
B) the tendency for a molecule to release OH^- in solution
C) the tendency of a molecule to accept electrons
D) the tendency of a molecule to donate electrons
E) a synonym for chemical valence

Question 10

What are the units of E°'?

A) kJ/mol
B) kcal/mol
C) mV
D) ohm
E) faraday

Question 11

Which of the following can be used to measure $\Delta$$\varPsi$ ?

A) lipid-soluble cations
B) membrane-permeant weak acids
C) oxidoreductases
D) cytochromes
E) uncoupling agents

Question 12

In some electron carriers, a __________ and __________ offer electrons with relatively narrow energy transitions.

A) dehydrogenase; oxidases
B) heteroatom; peptide bonds
C) metal ion; aromatic bonds
D) none of the above
E) all of the above

Question 13

The chemiosmotic theory states that the proton potential is composed of __________.

A) [ATP] and [ADP]+[Pi]
B) a pH gradient and a Na⁺ gradient
C) pH and pNa⁺
D) $\Delta$ pH and $\Delta$$\varPsi$
E) none of the above

Question 14

In Gram-negative bacteria, the ETS is embedded in the:

A) inner membrane
B) cell wall
C) periplasm
D) outer membrane
E) none of the above

Question 15

The chemiosmotic model does NOT explain synthesis of ATP in __________.

A) the chloroplast thylakoid membrane
B) the inner mitochondrial membrane
C) substrate-level phosphorylations
D) the purple bacteria thylakoids
E) inner membranes of Gram-negative bacteria

Question 16

The proton motive force drives the following process in bacteria:

A) ATP biosynthesis from ADP and Pi
B) flagellar rotation
C) nutrient uptake
D) all of the above
E) none of the above

Question 17

In the electron transport system, each cytochrome receives the electrons from a stronger __________ and transfers them to a stronger __________.

A) nitrogen compound series; sulfur compound series
B) reductant; oxidant
C) inorganic donor; organic donor
D) all of the above
E) none of the above

Question 18

Which of the following is NOT true of 2,4-dinitrophenol (DNP)?

A) It is an uncoupler.
B) It can be used to measure $\Delta$ pH.
C) Unprotonated DNP can cross the membrane.
D) Protonated DNP can cross the membrane.
E) It dissipates the proton motive force.

Question 19

NADH has more reducing power than FADH₂, therefore __________.

A) oxidation of NADH will contribute to form a larger $\Delta$ p and more ATP
B) both FADH₂ and NADH can be used by respiratory ETS, but FADH₂ will produce a lower ATP yield
C) the NADH + H⁺/NAD⁺ redox pair has a more negative E°' value than the FAD/FADH₂ pair
D) all of the above
E) none of the above

Question 20

A special kind of __________ flows among membrane-embedded proteins and cofactors, generating a(n) __________.

A) proton current; ion gradient
B) electrical current; pH gradient
C) electrical current; proton current
D) all of the above
E) none of the above

Question 21

Which kind of ion gradient do extreme halophilic archaea exclusively utilize?

A) proton
B) sodium ion
C) potassium ion
D) calcium ion
E) magnesium ion

Question 22

The following is NOT correct about the process of methanogenesis:

A) CO₂ and H₂O are weak electron acceptors, whereas CH₄ and H₂ are strong electron donors.
B) CH₄ synthesis from CO₂ releases energy for growth.
C) CH₄ and water can be formed from CO₂ and 4H₂ from a hydrogen donor.
D) Oxygen atoms in CO₂ are reduced one at a time.
E) Oxygen atoms in CO₂ are reduced to water at the same time.

Question 23

Sulfolobus species produce __________; as a result, their immediate environment has a pH as low as __________.

A) H₂SO₄; 2
B) H₃PO₄; 0
C) HCl; 1
D) CH₃COO^-; 4
E) none of the above

Question 24

The anammox reaction consists of:

A) reduction of sulfate by ammonia
B) reduction of ammonium to form nitrite
C) anaerobic ammonium oxidation by nitrite
D) reduction of ammonium by oxygen
E) the use of ammonium in amino acid biosynthesis

Question 25

Which of the following is NOT a terminal electron acceptor in anaerobic respirations?

A) nitrate
B) nitrite
C) sulfate
D) carbon dioxide
E) hydrogen sulfide

Question 26

In anaerobic soils, some yeasts and filamentous fungi can reduce nitrate to nitrite and nitrite to:

A) ammonia (NH₃)
B) nitric oxide (NO)
C) urea
D) all of the above
E) none of the above

Question 27

Ferroplasma acidarmanus produces large amounts of sulfuric acid through __________.

A) oxidation of Cu⁺ with Cu(NO₃)₂
B) oxidation of FeS₂ with Fe³⁺
C) oxidation of Fe₃O₂ with Fe²⁺
D) all of the above
E) none of the above

Question 28

Neisseria species are known to use dissimilatory reduction of nitrate to ammonium. How can this reaction be used to distinguish Neisseria gonorrhoeae from other related species?

A) N. gonorrhoeae will test negative for terminal NOreductase.
B) N. gonorrhoeae will test positive for terminal NOreductase.
C) All Neisseria species test negative for terminal NOreductase.
D) None of the enzymes involved in dissimilatory reduction of nitrate are known from Neisseria.
E) None of the above.

Question 29

Anaerobic corrosion of steel is accelerated by __________.

A) nitrifiers
B) sulfur-reducing bacteria
C) methanogenic archaea
D) all of the above
E) none of the above

Question 30

Alkaliphiles maintain an inverted pH gradient in which:

A) the pH in their immediate environment is lower than the cytoplasmic pH
B) their immediate environment has a pH several units above that of the cytoplasm
C) pH in the immediate environment is equal to that of the cytoplasm
D) all of the above
E) none of the above

Question 31

The following is correct with respect to dehalorespiration:

A) It is a type of hydrogenotrophy.
B) Cl^- can be removed from toxic compounds by dehalorespiration.
C) Hydrogenotrophs can be used in bioremediation.
D) All of the above.
E) None of the above.

Question 32

In seawater, sulfate is the most common anion after chloride. The following is correct with respect to the use of oxidized sulfate by some bacterial groups:

A) Oxidized sulfur molecules have potentials lower than those of the nitrogen series.
B) Oxidized sulfur molecules such as sulfate and sulfite serve as electron acceptors.
C) Sulfate and sulfite can receive electrons from hydrocarbons.
D) Sulfate-reducing archaea and bacteria are widespread in the ocean.
E) All of the above.

Question 33

What is the chromophore group in bacteriorhodopsin?

A) tochopherol
B) $\beta$ -carotene
C) folic acid
D) retinal
E) none of the above

Question 34

Which organism oxidizes copper and iron sulfides?

A) Geobacter metallireducens
B) Sulfurospirillum barnesii
C) Haloferax volcanii
D) Thiobacillus ferrooxidans
E) Bacillus subtilis

Question 35

Bacterial activity in Earth's crust may have deposited most of the gold through the process of __________.

A) reduction of hydrosoluble Au³⁺
B) oxidation of Au³⁺
C) oxidation of gold ores
D) all of the above
E) none of the above

Question 36

The reduction of uranium to uranite by Geobacter metallireducens is an example of:

A) assimilatory metal reduction
B) fermentation
C) dissimilatory metal reduction
D) organotrophy
E) lithotrophy

Question 37

In dehalorespiration of chlorinated pollutants, the chlorine is removed and replaced by:

A) hydrogen
B) oxygen
C) nitrogen
D) sulfur
E) ammonia

Question 38

Which one of the following enzymes is embedded in the membrane as an ETS component?

A) pyruvate dehydrogenase
B)2-oxaloglutarate dehydrogenase
C) succinate dehydrogenase
D) aconitase
E) none of the above

Question 39

In marine sediments, CO₂ is reduced to CH₄ by __________.

A) bacteria containing proteorhodopsin
B) oxygenic cyanobacteria
C) methanotrophic archaea
D) methanogenic archaea
E) none of the above

Question 40

The F_o portion of Escherichia coli ATP synthase that rotates while translocating protons is:

A) the $\gamma$ drive shaft
B) the a proton channel
C) a ring of 12 c subunits
D) an $\alpha\beta$ -subunit
E) none of the above

Question 41

The F₁F_o ATP synthase is a remarkably complex enzymatic complex, its subunit structure highly conserved across life domains. Is it possible to use this enzyme as an antibiotic target?

Question 42

What is the direction of proton backflow in the chloroplast F₁F_o ATP synthase?

A) from stroma to cytoplasm
B) from cytoplasm to stroma
C) from lumen to stroma
D) from stroma to lumen
E) none of the above

Question 43

Electron donors for anaerobic photosystem I in "green sulfur" bacteria include __________.

A) H₂S
B) organic molecules
C) Fe²⁺
D) all of the above
E) none of the above

Question 44

Bacterial cells use various membrane pumps and metabolic pathways to adjust and maintain their proton motive force at a size sufficient to drive ATP synthesis and other processes. Why should the proton motive force (PMF) not be larger than necessary? Give an example of a factor affecting PMF generation.

Question 45

What is the electron donor in anaerobic photosystem II?

A) H₂S
B) bacteriochlorophyll
C) quinol
D) all of the above
E) none of the above

Question 46

In purple bacteria, bacteriochlorophylls are supplemented by accessory pigments called:

A) antenna complexes
B) bacteriorhodopsin
C) carotenoids
D) chlorophylls
E) thylakoids

Question 47

Is the synthesis of ATP by the F_oF₁ ATPase reversible? If so, are there any examples?

Question 48

What could be the advantages of having a Na⁺-pumping oxidoreductase in pathogens such as Vibrio cholerae and Yersinia pestis?

Question 49

The following is correct with respect to anaerobic photosystem I:

A) PS I separates electrons associated with hydrogens from H₂S.
B) PS I separates electrons from organic electron donors such as succinate.
C) PS I separates electrons from Fe²⁺.
D) All of the above.
E) None of the above.

Question 50

Describe Peter Mitchell's chemiosmotic model for coupling ETS with ATP synthesis.

Question 51

How has the Geobacter metallireducens redox energy been harnessed in the production of electricity?

Question 52

In oxygenic photosynthesis, __________ is the electron donor, whereas in anaerobic photosynthesis it can be succinate or __________.

A) H₂S; S⁰
B) O_2; H₂
C) O_2; H₂O
D) H₂O; H₂S
E) all of the above

Question 53

The chlorophyll chromophore consists of a heteroaromatic ring complexed to a __________.

A) calcium ion
B) chloride ion
C) magnesium ion
D) manganese ion
E) potassium ion

Question 54

In Rhodospirillum rubrum photosystem II, bacteriochloropyll P870 can absorb weak infrared wavelengths in the __________ range.

A) 65-700
B) 750-850
C) 800-1,100
D) all of the above
E) none of the above

Question 55

How does bacteriorhodopsin couple photoexcitation with proton pumping?

A) Bacteriorhodopsin has a proton channel domain.
B) Bacteriorhodopsin makes the membrane porous to protons.
C) Light-induced conformational changes of retinal cause the protein to extrude one proton.
D) All of the above.
E) None of the above.

Question 56

Cyanobacteria have __________-based photosynthesis and are the only __________-producing bacteria.

A) H₂S; S⁰
B) Mg²⁺; NO
C) H₂O; O₂
D) succinate; O₂
E) none of the above

Question 57

Describe how an uncoupler functions. Can it be used as an antibiotic to treat bacterial infections?

Question 58

Why and how is it that mitochondria have only a single ETS, unlike many bacteria?

Question 59

How can $\Delta$ p be measured in bacterial cells? Compare that with ways to measure it in eukaryotic cells.

Question 60

How does the endosymbiont theory explain that the electron transfer system (ETS) in eukaryotes is located in the inner mitochondrial membrane?

Question 61

Describe the role of the thylakoids in purple bacteria. Why is it that pumping protons into the lumen is essentially equivalent to pumping protons out of the cell?

Question 62

How does bacteriorhodopsin couple photoexcitation with proton pumping? How is ATP synthesized in bacteriorhodopsin-containing organisms?

Question 63

What are facultative phototrophs? Provide an example and possible use in biotechnology.

Question 64

What is dissimilatory metal reduction? How is it different from assimilatory metal reduction?

Question 65

What is photoheterotrophy? Give examples of photoheterotrophic organisms.

Question 66

What are methanotrophs? What is their role in the global carbon cycle?

Question 67

How does photosystem I allow Chlorobium and other "green sulfur" bacteria to live near deep-sea vents?

Question 68

What are nitrifiers? What harms and benefits may they have for human activities?

Question 69

Explain what kind of reaction bacteriorhodopsin performs and what it accomplishes for the cell. What is the name of the bacteriorhodopsin homologs, in what type of organisms were they identified, and what led to their discovery?

Question 70

Electricity production by metal-reducing bacteria is a possibility. Describe how a metal with multiple redox states can be used to produce an electrical current.