Deck 3: Microbial Metabolism

Question 1

Based on the functional roles of phosphate in various microbial metabolisms, which of the following compounds most likely contain phosphate?

A) organic compounds
B) inorganic compounds
C) both organic and inorganic compounds
D) neither organic nor inorganic compounds

Answer 1

C

Question 2

Aseptic technique refers to

A) the microbial inoculum placed into a test tube or onto a Petri plate.
B) a series of practices to avoid contamination.
C) the autoclave and other sterilizing procedures.
D) cleanliness in the laboratory.

Answer 2

B

Question 3

The sum of all biosynthetic reactions in a cell is known as

A) metabolism.
B) anabolism.
C) catabolism.
D) synthatabolism.

Answer 3

B

Question 4

Which is an example of a micronutrient?

A) arginine
B) inorganic phosphorous
C) iron
D) vitamin B12

Question 5

A catalyst

A) requires more reactants but makes the reaction rate faster.
B) increases the amount of reactants produced but does not change the rate.
C) changes the rate of the reaction but does not change the end amount of products.
D) changes both the rate of a reaction and the amount of the product that will be obtained as the reaction is completed.

Question 6

The class of macromolecules in microorganisms that contributes most to biomass is

A) carbohydrates.
B) DNA.
C) lipids.
D) proteins.

Question 7

Which of the following statements is FALSE?

A) Most bacteria are capable of using ammonia as their sole nitrogen source.
B) Some bacteria are able to use nitrates or nitrogen gas as their nitrogen source.
C) Most available nitrogen is in organic forms.
D) Nitrogen is a major component of proteins and nucleic acids.

Question 8

What is the difference between a coenzyme and a prosthetic group?

A) Coenzymes are essential for an enzymeʹs function and prosthetic groups only enhance its reaction rate.
B) Coenzymes are weakly bound whereas prosthetic groups are strongly bound to their respective enzymes.
C) Coenzymes are organic cofactors and prosthetic groups are inorganic cofactors.
D) Coenzymes require additional ions to bind to enzymes but prosthetic groups are able to directly interact with enzymes.

Question 9

The portion of an enzyme to which substrates bind is referred to as the

A) substrate complex.
B) active site.
C) catalytic site.
D) junction of van der Waals forces.

Question 10

The prokaryotic transport system that involves a substrate-binding protein, a membrane-integrated transporter, and an ATP-hydrolyzing protein is

A) the ABC transport system.
B) group translocation.
C) symport.
D) simple transport.

Question 11

Which element functions BOTH as an enzyme cofactor and as a stabilizer of ribosomes and nucleic acids?

A) iron
B) hydrogen
C) zinc
D) magnesium

Question 12

All microorganisms require

A) carbon, iron, and sodium.
B) phosphorus, aluminum, and sodium.
C) calcium, potassium, and magnesium.
D) phosphorus, selenium, and sulfur.

Question 13

A chemoorganotroph and a chemolithotroph in the same environment would NOT compete for

A) oxygen.
B) carbon.
C) nitrogen.
D) phosphorous.

Question 14

Which of the following would be used by a chemoorganotroph for energy?

A) C₂H₃O₂⁻
B) H₂
C) CO₂
D) H⁺

Question 15

If ΔG⁰ʹ is negative, the reaction is

A) exergonic and requires the input of energy.
B) endergonic and requires the input of energy.
C) exergonic and energy will be released.
D) endergonic and energy will be released.

Question 16

Activation energy is the energy

A) required for a chemical reaction to begin.
B) given off as the products in a chemical reaction are formed.
C) absorbed as ΔG⁰ʹ moves from negative to positive.
D) needed by an enzyme to catalyze a reaction without coenzymes.

Question 17

To ensure growth of a newly discovered bacterium with unknown nutritional requirements, it would be best to begin with a ________ medium rather than a ________ medium.

A) complex / minimal
B) minimal / complex
C) selective / complex
D) selective / differential

Question 18

Based on your understanding of metabolism, generalize when an enzymeʹs rate of activity can be changed.

A) before enzyme production
B) during enzyme production
C) after enzyme production
D) at any point-before, during, or after enzyme production

Question 19

The change in Gibbs free energy for a particular reaction is most useful in determining

A) the amount of energy catalysts required for biosynthesis or catabolism.
B) the potential metabolic reaction rate.
C) whether there will be a requirement or production of energy.
D) energy stored in each compound.

Question 20

If an oxidation reaction occurs

A) simultaneous reduction of a different compound will also occur, because electrons do not generally exist alone in solution.
B) another oxidation reaction will occur for a complete reaction, because one oxidation event is considered a half reaction.
C) a cell is undergoing aerobic respiration, because oxygen is being used.
D) a reduction reaction would not occur, because they are opposite reaction mechanisms.

Question 21

During electron transport reactions

A) OH⁻ accumulates on the outside of the membrane while H⁺ accumulates on the inside.
B) OH⁻ accumulates on the inside of the membrane while H⁺ accumulates on the outside.
C) both OH⁻ and H⁺ accumulate on the inside of the membrane.
D) both OH⁻ and H⁺ accumulate on the outside of the membrane.

Question 22

Which of the following is a common energy storage polymer in microorganisms?

A) acetyl~S-CoA
B) glycogen
C) adenosine triphosphate
D) H₂

Question 23

The Embden-Meyerhof-Parnas pathway is another name for

A) the citric acid cycle.
B) glycolysis.
C) electron transport.
D) NADH production.

Question 24

Improperly functioning acyl carrier proteins (ACPs) would likely result in

A) a physiological shift to anaerobic metabolism where an energized membrane is less important for energy production.
B) enhanced growth of a bacterium due to faster growth substrate uptake by a weakened membrane.
C) no harm to bacteria, because only archaeons and eukaryotes use ACPs for fatty acid biosynthesis.
D) death for a bacterium due to poor lipid bilayer integrity.

Question 25

In aerobic respiration, the final electron acceptor is

A) hydrogen.
B) oxygen.
C) water.
D) ATP.

Question 26

All of the following are non-protein electron carriers EXCEPT

A) FADH₂.
B) FMNH₂.
C) cytochromes.
D) quinones.

Question 27

The rising of bread dough is the result of

A) biotin production.
B) carbon dioxide produced by fermentation.
C) oxidative phosphorylation.
D) oxygen being released.

Question 28

How does the proton motive force lead to production of ATP?

A) ATPase requires one proton to make one ATP.
B) Protons must be pumped against a concentration gradient from outside of the cell into the cell to rotate the F₀ subunit of ATPase for the F₁ subunit to make ATP.
C) Oxidative phosphorylation of ADP by ATP synthase requires protons as cofactors in the reaction.
D) Translocation of three to four protons drives the F₀ component of ATPase which in turn phosphorylates one ADP into ATP.

Question 29

For a carbon source, chemoorganotrophs generally use compounds such as

A) acetate, succinate, and glucose.
B) bicarbonate and carbon dioxide.
C) nitrate and nitrite.
D) acetate, bicarbonate, and nitrate.

Question 30

Which is one major difference between anaerobic and aerobic respiration?

A) electron donor
B) electron acceptor
C) use of electron transport
D) use of proton motive force

Question 31

A bacterium running low on NADPH could ________ to generate more of this coenzyme.

A) degrade an amino acid or nucleic acid
B) invoke the pentose phosphate pathway
C) degrade a fatty acid
D) use a broad specificity phosphatase with inorganic phosphatase and NADH

Question 32

Which two metabolic processes are most dissimilar?

A) citric acid cycle and glycolysis
B) glycolysis and gluconeogenesis
C) proton motive force and substrate-level phosphorylation
D) pentose phosphate pathway and glycolysis

Question 33

Which of the following is NOT membrane-associated?

A) NADH dehydrogenases
B) flavoproteins
C) cytochromes
D) Cytochromes, flavoproteins, and NADH dehydrogenases all can be membrane-associated.

Question 34

Fermentation has a relatively low ATP yield compared to aerobic respiration because

A) more reducing equivalents are used for anaerobic catabolism.
B) less ATP is consumed during the first stage of aerobic catabolism.
C) oxidative phosphorylation yields a lot of ATP.
D) substrate-level phosphorylation yields a lot of ATP.

Question 35

Microbial growth on the two-carbon acetate substrate invokes

A) the citric acid cycle for aerobic catabolism.
B) both the citric acid and glyoxylate pathways.
C) the glyoxylate pathway.
D) the glyoxylate and glycolysis pathways.

Question 36

Which intermediate compound(s) in the citric acid cycle is/are often used for biosynthetic pathways as well as carbon catabolism?

A) only α-ketoglutarate
B) only oxaloacetate
C) only succinyl-CoA
D) α-ketoglutarate, oxaloacetate, and succinyl-CoA

Question 37

Five-carbon sugars are used in the

A) biosynthesis of DNA and RNA.
B) catabolic pentose phosphate pathway for carbon and energy.
C) biosynthesis of DNA and RNA as well as catabolic pentose phosphate pathway.
D) activation of pentoses to form glycogen for energy storage.

Question 38

The net gain of ATP per molecule of glucose fermented is

A) 1.
B) 2.
C) 4.
D) 8.

Question 39

From the standpoint of fermentative microorganisms, the crucial product in glycolysis is

A) ATP and regenerated NAD⁺; the fermentation products are waste products.
B) ethanol or lactate; ATP is a waste product.
C) CO₂; ATP is a waste product.
D) not relevant because glycolysis is not a major pathway.

Question 40

A chemoorganotroph and a photoautotroph in the same environment would NOT compete for

A) oxygen.
B) carbon.
C) nitrogen.
D) carbon and oxygen.

Question 41

Regeneration of oxaloacetate is essential for the citric acid cycle to be cyclical.

Question 42

Hypothetically, if free electrons existed in sufficient numbers for enzymes to use in metabolic reactions

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

Question 43

Nitrogenases not only reduce N₂ but also can act on acetylene (C₂H₂).

Question 44

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

Question 45

The proton motive force is most often generated by splitting of H₂.

Question 46

If a substance is reduced, it gains electrons.

Question 47

A bacterial isolate that grows better on a nutrient agar plate supplemented with amino acids but still grows in a nutrient agar plate lacking amino acids suggests amino acids are trace nutrients for the isolate.

Question 48

Biosynthesis of glucose can occur by compounds other than sugars via gluconeogenesis.

Question 49

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

Question 50

Most of the carbon in amino acid biosynthesis comes from

A) citric acid cycle intermediates.
B) citric acid cycle intermediates and glycolysis products.
C) glycolysis products.
D) glycolysis intermediates and products.

Question 51

ATP-binding cassette transport systems have high substrate affinity and thus help microorganisms survive in low nutrient environments.

Question 52

One example of an electron acceptor that can be used in anaerobic respiration is

A) NADH.
B) water.
C) nitrate.
D) FMN.

Question 53

Each amino acid made during protein biosynthesis first requires a separate biosynthetic pathway to be invoked by a cell.

Question 54

Which metabolic strategy does NOT invoke the proton motive force for energy conservation?

A) aerobic catabolism
B) fermentation
C) chemoorganotrophy
D) photoautrophy

Question 55

Which metabolic cycle or pathway is LEAST likely to be invoked during the biosynthesis of DNA?

A) citric acid cycle
B) glycolysis
C) gluconeogenesis
D) pentose phosphate pathway

Question 56

When culturing a chemoorganoheterophic bacterium, what outcome is LEAST likely to occur if ammonia and phosphate are provided at equal concentrations?

A) Cells require much less P to grow than N, so extra P will be used for ATP synthesis and result in a faster growth rate.
B) Cells will never consume all of the phosphate, because N is needed in higher quantities than P.
C) The final biomass of cells will be no different than if only 50% of the phosphate was provided.
D) The bacteria will import all of the ammonia to use for biosynthetic pathways.

Question 57

Free-energy calculations are dependent on the rates of the reactions.

Question 58

Due to the number of phosphate groups, ATP has approximately three times more energy stored than AMP, and ADP has approximately two-thirds the energy stored of ATP.

Question 59

With respect to nitrogen utilization, relatively few bacteria can use NH₃ whereas many more can make use of N₂.

Question 60

In a given chemical reaction, if the free energy of formation is known for all of the reactants and each of the products, the change in free energy can be calculated for the reaction.

Question 61

A bacterium that lacks an arginine biosynthetic pathway would still be able to make proteins with arginine and grow only if arginine is supplemented into the growth medium.

Question 62

Varied coenzyme availability increases the diversity of enzymatic reactions in both biosynthetic and catabolic pathways possible in a cell.

Question 63

The energy released from the hydrolysis of coenzyme A is conserved in the synthesis of ATP.

Question 64

Explain the differences between symporters, and antiporters.

Question 65

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

Question 66

In electron transport systems, the electron carriers are membrane associated.

Question 67

During the electron transport process, protons and electrons become physically separated in the cell membrane.

Question 68

Summarize the roles the proton motive force has in microbial metabolism.

Question 69

In substrate-level phosphorylation, ATP storage is depleted during the steps in catabolism of the fermentable compounds.

Question 70

Compare and contrast defined media and complex media. Use specific examples in your answer.

Question 71

Molybdenum is a cofactor for nitrogenase, which means every nitrogen-fixing microorganisms will not be able to fix nitrogen without Mo.

Question 72

Why is energy required for nutrient transport? Give an example of a system that transports nutrients and describe what source of energy is used to move the nutrients into the cell.

Question 73

Magnesium is not considered a growth factor for microorganisms, because growth factors are always organic compounds.

Question 74

Cells require iron supplemented in their growth medium as a trace metal, because it is consumed by quinones during electron transport for ATP production.

Question 75

Many defined growth media that support microbial growth lack malonate, which is an important precursor for biosynthesis of lipid membranes. Based on this, we can infer cells also must have a metabolic pathway to generate malonate from other compounds.

Question 76

Discuss why energy yield in an organism undergoing anaerobic respiration is less than that of an organism undergoing aerobic respiration.

Question 77

Categorize the circumstances under which the same substance (molecule) can be either an electron donor or an electron acceptor.

Question 78

Heme prosthetic groups are involved in electron transfer with quinones.

Question 79

The net result of electron transport is the generation of a pH gradient and an electrochemical potential across the membrane.

Question 80

Contrast fermentation and respiration in terms of electron donor, electron acceptor, type of ATP production, and relative number of ATP produced.