BIOL 221 Exam 2

At the molecular level, how is a proton gradient generated by the quinone loop?

A. Light causes the quinone to “flip” a proton to the outside of the membrane.

B. The quinone donates 2 protons to O2 to make water, which leaves the cell.

C. The quinone donates both H+and electrons, but FeS proteins only accept electrons.

D. The quinone, which is located in the periplasm, accepts H+from the cytoplasm.

E. Electrons in the quinone are excited by light, and end up in NADH, which creates the

PMF

C. The quinone donates both H+ and electrons, but FeS proteins only accept electrons

Compared to mitochondrial ETS (electron transport systems), bacterial ETS _____.

A. use far fewer quinones

B. use a much greater variety of terminal electron acceptors

C. do not have cytochromes

D. always generate much less of a PMF

E. typically involve 6 electron transport components rather than 5

B. Use a much greater variety of terminal electron acceptors

In oxygenic photosynthesis, as practiced in bacteria _____.

A. the electrons that are excited by light return to the same photosystem

B. the main photosynthetic reaction pigment is bacteriochlorophyll

C. the electrons have such low energy that they must be energized twice

D. oxygen is the terminal electron acceptor

E. there are two electron transport chains

E. There are two electron transport chains

hy are purple sulfur bacteria considered metabolically unique?

A. They use H2S as an electron donor.

B. They must perform reverse electron transport to make NADH.

C. They use only one photosynthetic reaction center.

D. They produce a PMF from photosynthetic electron transport.

E. They make oxygen as a byproduct of photosynthesis

B. They must perform reverse electron transport to make NADH

How are respiratory and photosynthetic electron transport chains similar?

A. Both use the same electron donor.

B. Both use the same terminal electron acceptor.

C. Both use heme-containing electron carriers.

D. Both are used to generate reducing power for the cell.

E. Both involve adding external energy to electrons

B. Both use home-containing electron carriers

Purple sulfur bacteria (PSB) must use reverse electron transport, but green sulfur bacteria (GSB) do not. Why

is there a difference?

A. GSB use noncyclic photosynthesis, whereas PSB use cyclic.

B. PSB do not make a PMF with their electron transport chain.

C. GSB use a bacteriochlorophyll with enough energy to donate its electrons directly to

ferredoxin.

D. GSB use two photosystems, thereby boosting electrons to higher energy levels.

E. Making the sulfur granules in PSB requires electrons from reverse electron transport.

C. GSB use a bacteriochlorophyll with enough energy to donate its electrons directly to ferredoxin

Which of the following is true for all electron carriers?

A. They must be capable of being oxidized and reduced.

B. They must be able to accept both H+and electrons.

C. They must be able to accept O2.

D. They are proteins with metal ions at the center.

E. In bacteria, they are only found in the cytoplasm.

A. They must be capable of being oxidized and reduced

During oxygenic photosynthesis, the terminal electron acceptor for the electron transport chain

involving photosystem II and plastoquinone is ______.

A. oxygen

B. NADP+

C. the reaction center of photosystem I

D. H2O

E. ATP

C. The reaction center of photosystem I

Which of the following is similar in all three photosynthetic mechanisms we discussed?

A. the way reducing power is formed

B. the use of water as an electron donor

C. the photosynthetic reaction center chlorophyll

D. the way ATP is formed

E. the electrons return to the reaction center from which they were oxidized

D. The way ATP is formed

Which of the following statements correctly describes the molecule at right?

A. it can only be reduced, not oxidized

B. it carries only electrons, not H+

C. it carries only H+, not electrons

D. it carries both electrons and H+

E. it carries electrons from glycolysis to the TCA cycle

B. It carries only electrons, not H+

Which of the following is true of the mitochondrial electron transport system in eukaryotes, but

NOT always true of bacterial electron transport systems?

A. cytochrome c oxidase is always the final electron transport complex

B. several terminal electron acceptors can be used simultaneously

C. the number of H+pumped can vary depending on the needs of the cell

D. a quinone loop is used to couple electron transport to proton pumping

E. the initial electron donor is the oxidized form of NAD

A. Cytochrome c oxidase is always the final electron transport complex

Some photosynthetic bacteria need to generate reducing power by reverse electron transport because ____.

A. their electron donor has too few electrons to reduce NAD

B. their photosystems are inverted in the membrane

C. they use plant-type chlorophyll instead of bacteriochlorophyll

D. they perform only cyclic photosynthesis

E. their photosynthetic electron acceptor lacks the energy to donate electrons to NAD+

E. Their photosynthetic electron acceptor lacks the energy to donate electrons to NAD+

Why do most photosynthetic bacteria produce a complex containing antenna pigments?

A. it allows them to use multiple electron acceptors in their electron transport chains

B. the antenna complex oxidizes water to O2 for use in respiration

C. it allows them to channel additional photons of light to the reaction center

D. electrons from the antenna complex can be used to produce additional ATP

E. it allows them to increase the energy level of the photosynthetic reaction cente

C. It allows them to channel additional photons of light to the reaction center

During a reaction in the electron transport chain, an electron acceptor ______.

A. must also accept H+

B. must have more energy than the electron donor

C. must be a protein

D. must be able to synthesize ATP

E. must be reduced by the electron donor

E. Must be reduced by the electron donor

In an electron transport chain, proteins 1 and 2 (P1 and P2)

are structured as shown in the diagram. Which of the following

most accurately describes the roles of these proteins?

A. P1 contributes H+to the PMF, but P2 does not.

B. P2 contributes H+to the PMF, but P1 does not.

C. Both P1 and P2 contribute H+to the PMF.

D. P1 produces the PMF that P2 turns into ATP.

E. P2 produces the PMF that P1 turns into ATP

A. P1 contributes H+ to the PMF, but P2 does not

Which of the following correctly describes the direct mechanism of chemiosmotic ATP synthesis?

A. An ATP Synthase accepts electrons to reduce ADP to ATP.

B. Energy from a H+gradient turns a rotor to push ADP and ~P together.

C. An enzyme attaches H+from the PMF to ADP to make ATP.

D. Energy released by hydrolysis is coupled by a rotary enzyme to the phosphorylation of ADP.

E. Due to membrane semi-permeability, ATP can enter the cell, but ADP cannot.

B. Energy from a H+ gradient turns a rotor to push ADP and ~P together

The following electron transport chain…

A. is an example of a fermentation pathway

B. cannot make a PMF

C. is an example of substrate-level phosphorylation

D. is a type of respiration

E. probably came from a mitochondrion

D. Is a type of respiration

The goal of reverse electron transport, as carried out by purple photosynthetic bacteria, is to _____.

A. make ATP

B. make NADH

C. make O2

D. return electrons to Photosystem 2

E. use energy from alternate wavelengths of light

B. Make NADH

Why is it important that some electron carriers carry both electrons and protons, while others carry

only electrons?

A. This is how the Q loop pumps protons across a membrane.

B. This is necessary for energy to be given from one molecule to another in redox reactions.

C. The carriers that are proteins carry both H+and electrons.

D. The ones that carry only electrons provide energy for cellular rotary motors.

E. For antiports to function, protons must go one way and electrons the other

A. This is how the Q loop pumps protons across a membrane

Which of the following statements most accurately compares how ATP is generated during cyclic

versus non-cyclic photosynthesis (PS)?

A. Reverse electron transport must be used to synthesize ATP during cyclic PS.

B. In non-cyclic PS, electrons from H2O are used to reduce ADP to ATP in Photosystem II.

C. ATP is made by oxidation during non-cyclic PS, but by reduction during cyclic PS.

D. There is no ATP made during cyclic PS, but there is during non-cyclic PS.

E. ATP is produced by the same mechanism during cyclic PS as it is during non-cyclic PS

E. ATP is produced by the same mechanism during cyclic PS as it is during non-cyclic PS

When comparing green sulfur and purple sulfur bacteria _____.

A. green sulfur bacteria generate O2; purple sulfur bacteria do not

B. green sulfur bacteria use chlorophyll; purple sulfur use bacteriochlorophyll

C. purple sulfur bacteria have a lower energy photosystem than green sulfur bacteria do

D. purple sulfur bacteria do not accumulate sulfur granules; green sulfur bacteria do

E. purple sulfur bacteria produce a form of hemoglobin to bind O2

C. Purple sulfur bacteria have a lower energy photosystem than green sulfur bacteria do

The outline of oxygenic photosynthesis is

shown, with electron transfer steps marked 1

through 5. Which step is responsible for

generation of reducing power?

A. electron transfer #1

B. when electrons are excited as at #2

C. electron transfer #3

D. when electrons are excited as at #4

E. electron transfer #5

E. Electron transfer #5

The use of an organic electron acceptor without producing a PMF from the electron transfer is

known as _____.

A. heterotrophy

B. fermentation

C. anaerobic respiration

D. organotrophy

E. This is never done. Electron transfer always produces a PMF

B. Fermentation

How does electron transport lead to the formation of a proton gradient?

A. A special rotary motor pumps out H+as electrons cause it to turn in the membrane.

B. A symport mechanism uses the membrane potential to transport electrons out of the

cell along with H+.

C. Electrons reduce H2O to O2, and the 2 H+are released to the outside of the cell by

diffusion.

D. An antiport mechanism pushes H+out as it takes electrons in.

E. One member of the transport chain is reduced by both H+and electrons, but only the

electrons are passed to the next member.

E. One member of the transport chain is reduced by both H+ and electrons, but only the electrons are passed to the next member

What is meant by oxidative phosphorylation?

A. Oxidation of ADP to ATP

B. Oxidation of ATP to ADP

C. Production of ATP during glycolysis or the TCA cycle

D. Production of ATP from the PMF using ATP Synthase

E. ANY transfer of phosphate during a redox reaction

D. Production of ATP from the PMF using ATP synthase

Why is non-cyclic photosynthesis also called "oxygenic" photosynthesis?

A. The electron acceptor for PSI is O2.

B. O2 is produced during the electron transfer from PSI to PSII.

C. The electron donor for PSII is H2O.

D. It uses the same respiratory chain as mitochondria, but in reverse.

E. It is usually an anaerobic process

C. The electron donor for PS II is H2O

Compare oxygenic photosynthetic (OPS) and respiratory (RES) electron transport chains.

A. OPS use chlorophyll in the places where RES use cytochromes

B. OPS uses reverse electron transport to make ATP, but RES uses the ATP Synthase

C. OPS does not produce a PMF, but RES does

D. They both use oxygen as the terminal electron acceptor, but use different donors

E. They both use quinones and cytochromes in a Q-loop to produce a PMF

E. They both use quinones and cytochromes in a Q-loop to produce a PMF

The chemical DCCD binds irreversibly to the proton binding site of the FOF1 ATP Synthase. What

is the most likely consequence if DCCD is added to a culture of a facultative anaerobe?

A. The cells will die because they can't produce ATP.

B. The flagellar rotation speed would briefly increase due to a larger PMF.

C. The ATP Synthase would rotate passively, but wouldn't produce ATP.

D. The cell would produce much less of a PMF.

E. The cell would be OK, since the H+binding site is not the place where ATP is made

B. The flagellar rotation speed would briefly increase due to a larger PMF

How does oxidative phosphorylation make ATP?

A. It oxidizes ADP to make ATP

B. It oxidizes glucose to make CO2

C. It oxidizes NAD to make NADH

D. It oxidizes electron carriers to make a PMF

E. It oxidizes oxygen to produce water

D. It oxidizes electron carriers to make a PMF

When asked to sketch the reaction scheme for

green sulfur photosynthetic bacteria on an exam one

year, a student presented the diagram at right. I tried to

find something he got correct to give him some credit.

What did he get correct?

A. The use of two photosystems

B. The way ATP is produced from electrons

C. The way NADPH is produced directly

D. The production of O2 from PSII

E. Nothing – he got a zero on this one

C. The way NADPH is produced directly

A major difference between quinones and hemes in the electron transport chain is that _____.

A. quinones can only be oxidized; hemes only reduced

B. quinones accept and donate both H+and electrons; hemes only electrons

C. quinones are produced in the TCA cycle; hemes come from glycolysis

D. quinones have a lower energy level than hemes do

E. quinones are a terminal electron acceptor; hemes an initial electron donor

B. Quinones accept and donate both H+ and electrons; hemes only electrons

Which of the following is NOT important in a bacterial electron transport chain when creating a

PMF?

A. Having oxygen as the terminal electron acceptor

B. Having electron acceptors with lower energy than the donors

C. Passing electrons between carriers near the periplasmic side of the membrane

D. Redox energy being used to open proton transport channels

E. The membrane being impermeable to charged ions

A. Having oxygen as the terminal electron acceptor

How could you best determine whether an unknown respiratory chain was from a bacterium or

from a eukaryotic mitochondrion?

A. Whether it used NADH as an electron donor or not

B. Whether it produced ATP directly or indirectly

C. Whether a different magnitude of PMF can be produced under different conditions

D. Whether cytochrome c were an electron acceptor or not

E. Whether it involved a quinone loop or not

C. Whether a different magnitude of PMF can be produced under different conditions

Which of the following best describes how ATP is produced by oxidative phosphorylation?

A. The PMF reduces NADH to ATP

B. The PMF adds a proton to ADP to make ATP

C. electrons from the transport chain turn a rotor to make ATP

D. electrons from the transport chain reduce ADP to ATP

E. The PMF turns a rotor which pushes ADP and phosphate together

E. The PMF turns a rotor which pushes ADP and phosphate together

What are the appropriate mechanisms by which excited electrons dissipate their energy and revert to the

ground state among the provided options?

A. Utilization of excess energy to facilitate chemical reactions

B. Transference of energy to adjacent molecules, elevating electrons to higher energy levels

C. fluorescence

D. A and B

E. All of the followings are correct

E. All of the following are correct

You notice a “rotten egg” smell coming from the black goo in the iron drain pipe in your kitchen.

You could get rid of the smell by adding which of the following?

A. Sulfate reducers

B. Purple sulfur bacteria

C. Methanogenic bacteria

D. Clostridial spores

E. Sulfur oxidizing bacteria

E. Sulfur oxidizing bacteria

Nitrifying bacteria cause a high biological oxygen demand (BOD) in a pond . . .

A. when NH4+is present, since they metabolize it with O2 as the electron acceptor.

B. when NO2-is present, since O2is required to reduce it.

C. whenever they are present, since they have a high growth rate.

D. when lots of organic matter is present, since they are organotrophs.

E. only when they are fixing nitrogen

A. When NH4+ is present, since they metabolize it with O2 as the electron acceptor

Rhizobium produces leghemoglobin . . .

A. as part of its electron transport chain

B. as an iron-rich nutrient

C. to allow it to carry out photosynthesis

D. to bind O2in order to protect nitrogenase

E. as a dormant resting stage instead of endospores

D. To bind O2 in order to protect nitrogenase

Which of the following uses mainly fats and oils as carbon sources, producing acids and CO2 by

fermentation?

A. Rhizobium

B. Clostridium

C. Propionibacterium

D. Pseudomonas

E. Caulobacter

C. Propionibacterium

If you see the following structure on a plant, you could conclude that . . .

A. The plant is producing food for a bacterium

B. A bacterium is fixing nitrogen for the plant

C. The plant is infected with a fungus

D. A bacterium on the plant is reducing sulfate

E. The respiration rate inside the structure is elevated, and [O2] is

reduced

A. The plant is producing food for a bacterium

This bacterium lives in packets of four cells, two of which have their DNA tightly surrounded by a

protein ring that protects it against extreme levels of radiation.

A. Pseudomonas

B. Myxobacterium

C. Bdellovibrio

D. Deinococcus

E. Streptomyces

D. Deinococcus

You live near a swamp, and notice the “rotten egg” smell of H2S. Having taken micro, you decide to

bacterially remediate the odor. Which of the following bacterial types would NOT be able to do

the job if added to the swamp?

A. Green sulfur bacteria

B. Sulfate reducing bacteria

C. Chemolithoautotrophs

D. Sulfur oxidizing bacteria

E. Photolithoautotroph

B. Sulfate reducing bacteria

What bacteria carry out the reaction marked "A" in

the nitrogen cycle?

A. Nitrate oxidizing bacteria

B. Nitrate reducing bacteria

C. Nitrogen fixing bacteria

D. Nitrifying bacteria

E. Denitrifying bacteria

E. Denitrifying bacteria

Because it has a large number of modular catabolic pathways that produce intermediates that feed

into glycolysis, this bacterium can catabolize almost anything. It is often used to break down

environmental pollutants in the process of bioremediation.

A. Pseudomonas

B. Rhizobium

C. Agrobacterium

D. Propionibacterium

E. Deinococcus

A. Pseudomonas

Agrobacterium tumifaciens is especially important to plant scientists. What is so special about it?

A. It makes a carbon source that plants can use to grow.

B. It fixes nitrogen in plant root nodules.

C. It forms cysts that help to aerate the soil.

D. It can be used to insert foreign DNA into plant cells.

E. It is an excellent bacterial model for the plant type of photosynthesis.

D. It can be used to insert foreign DNA into plant cells

This bacterium produces CO2 and acids from growth on fats and oils, such as are present on your

skin in hair follicles.

A. Propionibacterium

B. Pseudomonas

C. Rhizobium

D. Pyruvobacter

E. Deinococcus

A. Propionibacterium

You're an engineer working on a bridge repair project. You notice that the buried iron bridge

supports are coated in black, smelly ooze. What could you conclude is present in the soil?

A. Sulfate

B. Oxygen

C. Leghemoglobin

D. Nitrate

E. Sulfuric acid

A. Sulfate

The free-living nitrogen fixing bacterium Azotobacter has a much higher rate of cellular

respiration than other bacteria. Why?

A. It has a much larger need for ATP than other bacteria

B. Its respiratory chain is less efficient than usual, since it doesn't donate electrons to O2

C. To protect the enzyme nitrogenase from oxygen

D. It gives much of its energy to a parasitic symbiont

E. It needs oxygen in large amounts for the metabolically active cysts

C. To protect the enzyme nitrogenase from oxygen

The bacterium Agrobacterium tumifaciens is very important in plant biology. Why?

A. It causes economic damage to corn and soybeans.

B. It can form endospores, which can adhere to the underside of leaves.

C. It passes back and forth between plant cells, carrying communication molecules.

D. It inserts a plasmid into plant cells, and can therefore be used in genetic engineering.

E. It associates with the roots of legumes, "fixing" nitrogen in a form plants can use

D. It inserts a plasmid into plant cells, and can therefore be used in genetic engineering

This bacterium has well defined stalked and

flagellated poles, which interchange in alternate

generations of its life cycle, as shown.

A. Bdellovibrio

B. Caulobacter

C. Myxobacterium

D. Photobacterium

E. Streptomyces

B. Caulobacter

Sulfate reducing bacteria . . .

A. produce sulfide, which forms a black precipitate on buried iron surfaces

B. produce H2SO4, and are therefore often acidophiles

C. are all obligate aerobes

D. are frequently also methanogens

E. are a subcategory of the larger group known as "purple sulfur bacteria"

A. Produce sulfide, which forms a black precipitate on buried iron surfaces

Which of the following bacteria carry out fermentations important to the food industry in the

production of dairy products and sauerkraut?

A. Clostridium

B. Deinococcus

C. Lactic Acid Bacteria

D. Bdellovibrio

E. Myxobacteria

C. Lactic acid bacteria

Which of the following would be the most appropriate term to put

in the box marked "????" in the image at the right?

A. N2

B. denitrification

C. nitrogen fixation

D. nitrification

E. nitrate reduction

D. Nitrification

What problem do all nitrogen fixing bacteria have in common?

A. They are aerobes, but nitrogenase is damaged by oxygen.

B. They must somehow get into plant root cells without being detected.

C. They must be able to carry out photosynthesis underground in the soil.

D. They need a very broad metabolic capacity to survive in a nutrient-poor environment.

E. They experience a lot of DNA damage, and so need highly efficient repair systems

A. They are aerobes, but nitrogenase is damaged by oxygen

Sulfur oxidizing bacteria . . .

A. produce sulfide, which forms a black precipitate on buried iron surfaces

B. are frequently also methanogens

C. produce H2SO4, and are therefore often acidophiles

D. usually grow anaerobically, using sulfur as an electron acceptor

E. are a subcategory of the larger group known as "green sulfur bacteria"

C. Produce H2SO4 and are therefore often acidophiles

In the diagram of the Nitrogen cycle at the right, which of the

following bacteria could carry out the indicated step?

A. Agrobacterium

B. Azotobacter

C. Deinococcus

D. Nitrifying bacteria

E. Denitrifying bacteria

B. Azobacter

Which of the following are famous for their ability to sense the presence of other bacteria, secrete

slime trails and aggregate together by social gliding motility into large, complex, spore-producing

structures called "fruiting bodies."

A. Caulobacter

B. Bdellovibrio

C. Corynebacterium

D. Picrophilus

E. Myxobacterium

E. Myxobacterium

Some bacteria contain a large piece of circular DNA called the Ti plasmid. What is the purpose of

this plasmid?

A. to protect nitrogenase from the toxic effects of oxygen

B. to form symbiotic root nodules for nitrogen fixation

C. to increase the number of replication origins so that DNA replication is faster

D. to make an infected plant produce nutrients for the bacterium

E. to form cysts that allow the bacteria to survive harsh environmental conditions

D. To make an infected plant produce nutrients for the bacterium

The bacterium Caulobacter crescentus is well known for its ability to . . .

A. survive massive doses of radiation

B. produce light in response to cell density

C. produce endospores to survive starvation

D. grow in concentrated salt solutions

E. distinguish one end of its cell (stalk) from the other (flagella)

E. Distinguish one end of its cell (stalk) from the other (flagella)

Which of the following is an accurate comparison between sulfate reducing bacteria (SRB) and

sulfur oxidizing bacteria (SOB)?

A. SRB are aerobic; SOB are anaerobic.

B. SRB are lithotrophs; SOB are organotrophs.

C. SRB are phototrophs; SOB are chemotrophs.

D. SRB are generally undesirable; SOB can be used in biomining of sulfide ores.

E. SRB and SOB are closely related, and carry out very similar energy-generating reactions.

D. SRB are generally undesirable, SOB can be used in biomining of sulfide ores

Important industrial production of acetone, butanol and other organic solvents depends on . . .

A. Clostridial fermentation

B. fermentation of lipids

C. methanogenesis

D. the versatile metabolism of Pseudomonas

E. lactic acid fermentation

A. Clostridial fermentation

To check the quality of an agricultural soil you sometimes pull up certain plants and look for pink

lumpy structures on the roots. What do these structures indicate?

A. the plant has been infected by a tumor-forming bacterium

B. the soil is rich in a form of nitrogen that plants can use

C. the soil is contaminated by a fungus

D. the soil is rich in oxygen because of bacteria with a high BOD

E. there are cysts of certain bacteria in the soil near the plant

B. The soil is rich in a form of nitrogen that plants can use

Which of the following reactions is carried out by methanogenic Archaea?

A. CO2is reduced to CH4 using electrons from H2

B. CO2is reduced to CH4 using electrons from light

C. CH4is oxidized to CO2 using an organic electron donor

D. CH4is oxidized to CO2 using electrons from light

E. glucose is hydrolyzed to CO2 using energy from CH4

A. CO2 is reduced to CH4 using electrons from H2

Which of the following is true about Sulfate Reducing Bacteria?

A. They produce H2SO4 that makes their environment very acidic.

B. They are used in sewage treatment to remove ammonia waste.

C. Their presence in anaerobic soil is indicated by a "rotten egg" odor.

D. They use O2 as the terminal electron acceptor of an electron transport chain.

E. They use bacteriochlorophyll for photosynthetic energy generation

C. Their presence in anaerobic soil is indicated by a rotten egg odor

Which of the following bacteria both carry out fermentation reactions that are used in the

preparation of important food products?

A. Clostridium and Corynebacterium

B. Caulobacter and Bacillus

C. Leuconostoc and Deinococcus

D. Lactococcus and Propionibacterium

E. Streptomyces and Pseudomonas

D. Lactococcus and Propionibacterium

You notice that one part of a plant is covered with small pinkish spherical

structures, as shown in the picture at right. What can you conclude?

A. The soil in which the plant is growing must be anaerobic.

B. The spherical structures contain the enzyme nitrogenase.

C. The plant has been colonized by Azotobacter.

D. The plant has been infected by a tumor virus.

E. The nitrification process is being carried out in the spherical structures

B. The special structures contain the enzyme nitrogenase

Purple nonsulfur bacteria can grow both aerobically and anaerobically, but they use different

biochemical mechanisms to do so. How do these bacteria obtain reducing power when they are

growing anaerobically?

A. by using electrons from light to reduce NAD+

B. mainly by using redox reactions in the TCA cycle

C. from sulfur granules that are present in the environment around the bacteria

D. by using a photosynthetic PMF to reverse a part of the electron transport chain

E. by using a rotary enzyme in the cell membrane to turn the PMF into reducing power

D. By using a photosynthetic PMF to reverse a part of the electron transport chain

Which of the following are typically lithotrophs?

A. Sulfate Reducing Bacteria

B. Lactic Acid Bacteria

C. Propionibacteria

D. Pseudomonas

E. Nitrifying Bacteria

E. Nitrifying bacteria

How does Clostridial ABE fermentation differ from the lactic acid fermentation performed by

many other bacteria?

A. ABE fermentation can ferment lipids.

B. ABE fermentation reduces NAD, rather than oxidizing NADH.

C. ABE fermentation can produce some additional ATP.

D. ABE fermentation produces methane.

E. ABE fermentation is aerobic, but most other fermentation is anaerobic

C. ABE fermentation can produce some additional ATP

Deinococcus bacteria can be found uniquely in what environment?

A. Very low pH

B. Very high temperatures

C. Very high salt concentrations

D. Very high radiation levels

E. Very low nutrient levels

D. Very high levels

What bacteria would you expect to find in dense, pink or red clusters associated with plants?

A. Rhizobium

B. Streptomyces

C. Azotobacter

D. Denitrifying bacteria

E. Photobacterium

A. Rhizobium

What is Agrobacterium noted for?

A. Cultivation of fungal symbionts

B. Natural insertion of DNA into plant cells

C. Release of digestive enzymes in response to quorum sensing

D. Reduction of O2 concentration to allow nitrogenase to function

E. Invasion of the periplasm of other Gram negative bacteria

B. Natural insertion of DNA into plant cells

You are a soil scientist trying to bioremediate (use bacteria to clean up) an area of soil

contaminated by a pesticide. Which of the following bacteria would be your best choice to do this,

and why?

A. Pseudomonas, because it is adaptable to growth on many different carbon sources

B. Deinococcus, because it can survive in the presence of toxins

C. Clostridium, because it can use the energy in the pesticide to fix nitrogen

D. Corynebacterium, because it produces spores which can survive in soil

E. A methanogenic Archaea, because it can grow both aerobically and anaerobically

A. Pseudomonas, because it is adaptable to growth on many different carbon sources

Myxobacteria are noted best for their . . .

A. ability to survive at low pH

B. ability to produce light when crowded together

C. ability to fix nitrogen in the soil

D. ability to aggregate in response to quorum sensing

E. ability to produce many of the useful antibiotics

D. The ability to aggregate in response to quorum sensing

Which of the following has a unique cell cycle, in which only one of the two daughter cells is able

to replicate directly?

A. Deinococcus

B. Bdellovibrio

C. Caulobacter

D. Picrophilus

E. Streptomyces

C. Caulobacter

Instruments that are considered medically “critical” must be

A. sanitized

B. disinfected with a high level disinfectant

C. autoclaved

D. detoxified with an antitoxin

E. sterilized

E. Sterilized

Place the following organisms in order from HARDEST to kill to EASIEST.

(1) naked viruses

(2) Pseudomonas cells

(3) Bacillus endospores

(4) Giardia cysts

A. HARDEST (1) > (3) > (2) > (4) EASIEST

B. HARDEST (3) > (4) > (1) > (2) EASIEST

C. HARDEST (3) > (1) > (2) > (4) EASIEST

D. HARDEST (4) > (3) > (1) > (2) EASIEST

E. HARDEST (1) > (4) > (2) > (3) EASIEST

B. HARDEST (3) > (4) > (1) > (2) EASIEST

Which of the following methods would be acceptable to sterilize a chicken thigh that is intended for

long-term storage and eventual consumption (i.e. as part of a military ration)?

A. Dry heat

B. UV-irradiation

C. microwave irradiation

D. gamma ray irradiation

E. heating to 72oC for 15 seconds

D. Gamma ray irradiation

A mouthwash called “Hexodent” lists the following ingredients: 8% alcohol, 0.2% chlorhexidine,

mint flavor. How does this mouthwash kill bacteria?

A. The chlorhexidine dissolves cell membranes.

B. The chlorhexidine oxidizes proteins.

C. The alcohol denatures proteins.

D. The alcohol damages DNA.

E. Chlorhexidine + ethyl alcohol → ethylene oxide, which oxidizes DNA.

A. The chlorhexidine dissolves cell membranes

Using chlorox, it takes 20 minutes to decontaminate a water bottle with 104 Cryptosporidium cysts

in it. The decimal reduction time for this procedure is 10 minutes. Using the same method, how long

would it take to decontaminate the water bottle if it had 108 Cryptosporidium cysts?

A. 20 minutes

B. 40 minutes

C. 60 minutes

D. 80 minutes

E. There is not enough information to answer this question.

C. 60 minutes

What is the difference between high-level and low-level disinfectants?

A. High-level can kill Mycobacterium, low level often cannot

B. High-level are used on countertops, low-level on floors

C. High-level are used more as skin disinfectants; low-level for metal surfaces

D. Low-level can only kill spores, high-level can also kill growing cells

E. Low-level include things like ethylene oxide and formaldehyde

A. High-level can kill Mycobacterium, low level often cannot

Rank the following treatments in terms of numbers of organisms that can survive the procedure:

1: autoclave

2: high temperature, short time (HTST) pasteurization

3: boiling

4: microwaving (not in water)

A. MOST SURVIVORS (3) > (2) > (4) > (1) LEAST SURVIVORS

B. MOST SURVIVORS (4) > (2) > (3) > (1) LEAST SURVIVORS

C. MOST SURVIVORS (4) > (3) > (2) > (1) LEAST SURVIVORS

D. MOST SURVIVORS (1) > (4) > (3) > (2) LEAST SURVIVORS

E. MOST SURVIVORS (4) > (1) > (3) > (2) LEAST SURVIVORS

B. MOST SURVIVORS (4) > (2) > (3) > (1) LEAST SURVIVORS

Why are naked viruses more resistant to disinfection than enveloped viruses are?

A. Naked viruses have a tough outer layer that resists chemical treatment

B. Enveloped viruses require at least some water for the envelope to remain intact

C. Naked viruses have a more robust metabolism, and are harder to kill

D. Enveloped viruses have transport channels that allow disinfectants into the virus

E. They aren’t. It is enveloped viruses that are more resistant to disinfectants.

B. Enveloped viruses require at least some water for the envelope to remain intact

How does UV light kill bacterial cells?

A. By cross-linking and rigidifying proteins

B. By damaging the cell membrane

C. By oxidizing cell macromolecules

D. By causing the cells to vibrate rapidly enough to shake them apart

E. By mutating the DNA

E. By mutating the DNA

Pasteurized milk . . .

A. contains no bacteria

B. has been heated briefly to 100oC

C. has been autoclaved

D. contains no endospores

E. can still have dozens of bacteria per ml

E. Can still have dozens of bacteria per mL

The decimal reduction time for disinfecting a Staphylococcus-contaminated steel countertop with

500 ppm chlorine bleach is 2 minutes. Which of the following would decrease the decimal reduction

time?

A. using 5000 ppm chlorine bleach rather than 500 ppm

B. disinfecting a rough surface such as a sieve or screen instead of smooth steel

C. disinfecting a greasy surface such as a dish drain instead of a countertop

D. disinfecting a surface contaminated with mycobacteria rather than Staphylococcus

E. using 70% ethanol rather than chlorine bleach

A. Using 5000 ppm chlorine bleach rather than 500 ppm

Iodine and its water-soluble derivative, betadine, are commonly used disinfectants. How do they

kill cells?

A. Damage DNA

B. Cross-link and rigidify proteins

C. Dissolve cell membranes

D. Dry out the cells by evaporation

E. Oxidize and denature proteins

E. Oxidize and denature proteins

Why is hydrogen peroxide (H2O2) considered high-level if used as a disinfectant, but only low

level if used as an antiseptic?

A. Skin contains catalase, which can make H2O2 less effective.

B. Antiseptics require a more rigorous definition of “sterile” than disinfectants.

C. Antiseptics are used to kill more resistant organisms than disinfectants.

D. H2O2 evaporates readily from inanimate surfaces, drying the surface more quickly.

E. H2O2 is toxic when used on skin, and thus can only be used on inanimate surfaces

A. Skin contains catalase, which can make H2O2 less effective

Which of the following is the best method for sterilizing an implanted cardiac pacemaker?

A. Microwave it

B. Soak it in ethyl alcohol overnight

C. Wash it with a quaternary ammonium compound (QUAT)

D. Irradiate it with gamma (γ) rays

E. A pacemaker is a semi-critical instrument and only needs to be clean, not sterile

D. Irridiate it with gamma (y) rays

Which of the following medical instruments is NOT matched properly with an antimicrobial

method that could be used to cleanse it?

A. Surgical sponge - Quaternary ammonium salt (QUAT)

B. Central venous (in vein) catheter - Ethylene oxide

C. Gastric (stomach) endoscope - Hydrogen peroxide

D. Tracheal (lung) endoscope - Glutaraldehyde

E. Examination table - Phenolic (e.g. Lysol)

A. Surgical sponge- Quaternary ammonium salt (QUAT)

Triclosan and Lysol both kill cells by damaging cell membranes. Bacterial resistance to Lysol is

unknown, but triclosan resistance has become a major medical problem. Why the difference?

A. Lysol also oxidizes proteins, so it is harder for bacteria to develop resistance.

B. Triclosan acts against a single enzyme, mutations in which allow resistance.

C. Lysol is a high-level disinfectant, triclosan only an intermediate-level one.

D. Triclosan damages the outer membrane, where resistance can develop more easily.

Lysol damages the inner membrane.

E. Triclosan has been used for a longer time than Lysol. Given time, bacteria will

develop Lysol resistance, too.

B.  Triclosan acts against a single enzyme, mutations in which allow resistance.

HTST pasteurization reduces bacterial contamination of milk by 5 logs in 15 seconds. What is the

decimal reduction time for this procedure?

A. 1 second

B. 3 seconds

C. 15 seconds

D. 75 seconds

E. there is insufficient information to answer the question

B. 3 seconds

A HEPA filter is used to filter the air in a hospital room. Filtered air is most likely to still contain .

. .

A. Endospores

B. Mycobacterium

C. Gram positive bacteria

D. Naked viruses

E. Pseudomonas

D. Naked viruses

The most practical way to decontaminate a semi-critical medical device made of soft plastic is to . .

A. autoclave it

B. wash it with a quaternary amine (QUAT) soap

C. wash it with betadine

D. soak it in 70% ethanol

E. soak it in 3% peroxide

D. Soak it in 70% ETOH

Which of the following is the most likely to be decontaminated by exposure to ethylene oxide?

A. a scalpel

B. the fluid in an IV (intravenous) drip bottle

C. a pacemaker

D. the operating room after a surgical procedure is completed

E. skin that is being prepared for surgery

C. A pacemaker

You are cleaning a food preparation surface with a disinfectant. Which of the following is the

hardest to kill, and why?

A. Enveloped viruses, because the tough envelope protects them from chemical damage

B. Naked viruses, because they have no sensitive external structures

C. Mycoplasma, because they are protected by a tough, waxy outer layer

D. Gram positive cells, because they have a very thick layer of protective peptidoglycan

E. Pseudomonas, because a dense protein coat protects it from chemicals, UV light, and heat

B. Naked viruses, because they have no sensitive external structures

Compared to a dry surface, an oily surface . . .

A. is likely to require a longer decimal reduction time for disinfection

B. will be more susceptible to dry heat than to steam

C. will probably require cleaning with antiseptics rather than with disinfectants

D. is easier to pasteurize but harder to sterilize

E. should have about the same properties as far as disinfection is concerned

A. Is likely to require a longer decimal reduction time for disinfection

Why can UV radiation be used to kill bacteria, but microwaves cannot?

A. Microwaves only sterilize a surface; they do not penetrate.

B. Microwaves heat only bacterial proteins, not membrane lipids.

C. Microwaves do not have enough energy to damage DNA.

D. Microwave wavelength is too short to interact with things as small as bacteria.

E. Microwaves CAN be used – they just have to be used for a longer time

C. Microwaves do not have enough energy to damage DNA

____________ is a low-level antiseptic that damages bacterial membranes. It is often used in

mouthwashes and skin care products.

A. Glutaraldehyde

B. Betadine

C. Chlorhexidine

D. Ethylene oxide

E. Formalin

C. Chlorhexidine

___________ are high-level disinfectants when used in the food industry, but only work at

intermediate level when used medically on human skin.

A. Peroxides

B. Phenolics

C. Quaternary ammonium salts (QUATs)

D. Alcohols

E. Biguanides

A. Peroxides