Microbial Metabolism [3]

Question 1

Hypothetically, if electron pools existed in sufficient numbers for enzymes to use in metabolic reactions,
A Q-cycle reactions would no longer be necessary for electron transport, but the proton motive force would otherwise be unchanged.
B cytochromes would be unnecessary for cells and quinones would be more important.
C a higher diversity of cytochromes would likely be observed.
D most metabolic pathways for both anabolism and catabolism would have to be rewritten.

Answer 1

D

Question 2

Depending on the particular metabolism of a bacterium, electron transport can be used to energize and rotate ATP synthase.
A True
B False

Answer 2

B

Question 3

The terminating step of moving electrons onto oxygen releases additional ATP during aerobic metabolism not made during anaerobic growth.
A True
B False

Answer 3

B

Question 4

Catabolic pathways are essential for microorganisms to obtain energy, because biosynthetic reactions for cellular growth generally require energy input.
A True
B False

Answer 4

A

Question 5

Which feature of anaerobic and aerobic respiration is different between the two catabolic strategies?
A electron acceptor
B use of proton motive force
C electron donor
D use of electron transport

Answer 5

A

Question 6

Which metabolic strategy does NOT utilize the proton motive force?
A anaerobic respiration
B aerobic respiration
C fermentation
D photosynthesis

Answer 6

C

Question 7

One example of an electron acceptor that can be used in anaerobic respiration is
A water.
B FMN.
C nitrate.
D NADH.

Answer 7

C

Question 8

How is anaerobic respiration different from aerobic respiration?
A The terminal electron acceptor in anaerobic respiration is oxygen.
B The two processes are identical. The only difference is the presence or absence of oxygen.
C The terminal electron acceptors are the same, but the chemical reactions are different.
D The terminal electron acceptor in anaerobic respiration is not oxygen.

Answer 8

D

Question 9

Chemolithotrophs that obtain electrons from donors such as sulfide use similar electron transport chains to obtain energy in a similar way from the electron transport chain as chemoorganotrophs.
A True
B False

Answer 9

A

Question 10

A bacterium that uses CO2 as an electron source but CANNOT use it as a carbon source is considered a mixotroph.
A True
B False

Answer 10

A

Question 11

Autotrophs are always \_\_\_\_\_\_\_\_\_\_.
A heterotrophs
B chemotrophs
C mixotrophs
D chemolithotrophs

Answer 11

D

PLANTS?
PHOTOLITHOTROPHS?

WHAT THEY MEAN TO SAY IS ALL CHEMOLITHOTROPHS ARE AUTOTROPHS

Question 12

The aerated upper layer of soil is likely to have ________ concentrations of H2 for aerobic H2-oxidizing Bacteria, so these bacteria likely ________.
A high / generate important reducing equivalents as byproducts for other microorganisms in the soil
B low / will need a chemoorganotrophic way to grow as well
C high / thrive in such conditions by not competing with chemoorganotrophs
D low / do not occur in such habitats

Answer 12

B

Question 13

In most cases, the final product of sulfur oxidation is
A elemental sulfur.
B sulfate.
C hydrogen sulfide.
D thiosulfate.

Answer 13

B

Question 14

What metabolic advantage do cells have in storing the elemental sulfur byproduct from sulfide oxidation?
A The byproduct serves as an electron reserve for subsequent oxidation.
B Sulfur decreases the intracellular acidification for non-acid-tolerant sulfide oxidizers.
C The byproduct can be used for other biosynthetic pathways that use sulfur, such as Rieske Fe-S proteins.
D The cells avoid producing transport energy waste to secrete the sulfur.

Answer 14

A

Question 15

A cell that lacks sulfite oxidase but can still oxidize sulfur for energy could be identified by
A adenosine phosphosulfate reductase coupled with substrate-level phosphorylation.
B quantifying the release of sulfate byproduct.
C electrons being transferred to cytochrome c prior to shuttling them into the electron transport chain.
D identifying an alternative quinone, flavoprotein, or cytochrome.

Answer 15

A

Question 16

Some sulfur-oxidizing bacteria can simultaneously reduce nitrate, which enables them to grow anaerobically.
A True
B False

Answer 16

A

Question 17

Ferrous iron (Fe2+) oxidation generally occurs in environments with
A high oxygen content.
B alkaline conditions.
C high H+ concentrations.
D little or no light present.

Answer 17

C

Question 18

Iron-oxidizing bacteria grow better in alkaline environments where protons are less likely to abiotically convert Fe2+ into Fe3+.
A True
B False

Answer 18

B

Question 19

Bacteria that are capable of oxidizing both iron and sulfur usually have a strong preference for sulfur oxidation because it yields more energy.
A True
B False

Answer 19

B

Question 20

AcetylCoA is an important molecule. It is produced from pyruvate (a three-carbon molecule) by a transition reaction in many organisms (acetylCoA serves as a substrate for the Krebs Cycle, citric acid cycle, and tricarboxylic acid cycle). This transition reaction releases CO2. Additionally, many organisms that use fermentation produce fatty acids, sometimes using acetylCoA. Why is acetylCoA so important in the formation of fatty acids?
A Having acetylCoA allows for more CO2 production, and having more CO2 provides more substrate for the Calvin cycle.
B The coenzyme A intermediate is required for fatty acid synthesis in microorganisms.
C AcetylCoA is important in regulation; its presence activates the enzymes used in beta-oxidation.
D AcetylCoA consists of a two-carbon acetate with coenzyme A. It is the building block for fatty acids; two carbons at a time are added by adding acetylCoA during the process. So, organisms that produce acetylCoA during fermentation have a two-carbon molecule that can easily be used to build fatty acids and that can also allow ATP to be generated in the process.

Answer 20

D

Question 21

Why will some organisms ferment, when the fermentation products are excreted and only very little of the original compound is used for biosynthesis?
A to conserve energy
B to utilize the electron transport chain
C to create more energy
D for oxidative phosphorylation

Answer 21

A

Question 22

If an organism used glycolysis (Embden-Meyerhof-Parnas pathway) but were unable to use fermentation or an electron transport chain, what problem would develop?
A The available NAD+ would be converted to NADH and glycolysis would stop due to the lack of NAD+.
B The cell will run out of ATP and glycolysis will stop.
C Glycolysis rates would increase in order to compensate for the lack of ATP produced by the other processes.
D The cell would run out of glucose and glycolysis would stop.

Answer 22

A

Question 23

The term “anaerobic respiration” is often used more broadly than is strictly accurate. Which of the examples below is the best example of anaerobic respiration?
A Purple bacteria use a type of photosynthesis that does not generate oxygen.
B An organism uses an electron transport chain with sulfur as the terminal electron acceptor.
C Lactic acid fermenters are able to generate energy in the absence of oxygen.
D Many organisms use an electron transport chain with oxygen as the terminal electron acceptor to generate relatively large quantities of ATP.

Answer 23

B

Question 24

The catabolism of lipids produces more energy per gram than the catabolism of carbohydrates or proteins. Why is this the case?
A Living organisms break down carbohydrates, proteins, and lipids through oxidation. Because lipids are more oxidized initially, more energy can be extracted during this process.
B Living organisms break down carbohydrates, proteins, and lipids through oxidation. Because lipids are more reduced initially, more energy can be extracted during this process.
C Living organisms break down carbohydrates, proteins, and lipids through reduction. Because lipids are more reduced initially, more energy can be extracted during this process.
D Living organisms break down carbohydrates, proteins, and lipids through reduction. Because lipids are more oxidized initially, more energy can be extracted during this process.

Answer 24

B

Question 25

Which statement explains how anaerobic respiration and aerobic respiration differ?
A There are different electron carriers depending on the type of respiration.
B In anaerobic respiration, the terminal electron acceptor is an inorganic compound.
C Only aerobic respiration utilizes the electron transport chain.
D None of the listed responses are correct.

Answer 25

D

Question 26

One result of the oxidation of reduced sulfur compounds is a rise in the pH of the medium.
A True
B False

Answer 26

B

Question 27

Oxidative phosphorylation is a critical process for many living organisms. Which of the following is an example of oxidative phosphorylation?
A A eukaryotic cell makes ATP using an electron transport chain with oxygen as the terminal electron acceptor.
B A prokaryotic cell produces ATP during the light reactions of photosynthesis.
C A eukaryotic cell produces ATP during glycolysis.
D A prokaryotic cell adds oxygen to an organic molecule that contains phosphate.

Answer 27

A

Question 28

How does Dr Stark measure e- transfer for his molecules?

Answer 28

Almost exclusively by mole of e- donor.