Microbiology Chapter 20

6) The primary energy source for termites comes from A) acetogenic Archaea. B) acetogenic Bacteria. C) methanogenic Archaea. D) methanogenic Bacteria.

B) acetogenic Bacteria.

10) Nitrate (NO3-) reduced into ammonia (NH3) to produce energy for the cell is called A) ammonification. B) dissimilative reduction of nitrate to ammonia (DRNA). C) nitrification. D) redox.

B) dissimilative reduction of nitrate to ammonia (DRNA).

35) The two major forms of carbon that remain following microbial degradation are A) methane, organic matter, and fossil fuels. B) methane and carbon dioxide. C) lignin and fossil fuels. D) organic matter and hydrocarbons.

B) methane and carbon dioxide.

39) Phosphonate comprises 25% of the ________ phosphorous pool in marine environments. A) inorganic B) organic C) insoluble D) biologically unavailable

B) organic

45) Nitrification and anammox both A) create nitrogen gas, but nitrification is aerobic while anammox is anaerobic. B) oxidize ammonia, but nitrification uses O2 and anammox uses NO2- for electron acceptors. C) are aerobic processes, but nitrification produces NO3- and annamox produces N2 gas. D) occur in soils at neutral pH.

B) oxidize ammonia, but nitrification uses O2 and anammox uses NO2- for electron acceptors.

9) The metabolic process of ammonification ________ ammonia. A) oxidizes B) produces C) reduces D) transforms

B) produces

31) What is the largest carbon sink on Earth? A) terrestrial biosphere B) rocks and sediments C) aquatic biosphere D) fossil fuels

B) rocks and sediments

12) The precipitation of soluble iron ions into solid iron occurs spontaneously in the presence of organic carbon compounds.

False

14) Energy yields are high enough for Fe2+ oxidation that the bacteria that perform this reaction require only small quantities of Fe2+ to be available.

False

16) Silicoflagellates use silicon compounds in substrate-level phosphorylation.

False

17) Carbon dioxide is the only greenhouse gas produced by anthropogenic activities.

False

20) The mercury in fish is normally in the form of elemental mercury (Hg0).

False

23) Microbial activity generates methylmercury, which is much less toxic than the mercuric ion.

False

25) Calcium is cycled most rapidly in terrestrial environments.

False

26) Denitrification of fertilizer can result in harmful algal blooms.

False

3) Humic acids are difficult to degrade, and therefore they usually remain in a system for several decades.

False

4) Climate scientists are developing methane hydrates to decrease the effects of global warming.

False

6) Methanogens, among other compounds, use alcohols and fatty acids to synthesize methane gas in anoxic environments.

False

9) When carbon is limiting in a system, sulfate reducers often predominate the system when sufficient sulfate ions are present for reduction.

False

8) The metabolic process of denitrification A) oxidizes N2. B) oxidizes NO3-. C) reduces N2. D) reduces NO3-.

D) reduces NO3-.

4) Frozen methane molecules are called A) anhydrous methane. B) anoxic methane. C) methane anhydrates. D) methane hydrates.

D) methane hydrates.

23) Mercury is NOT used in A) electronics. B) neurotoxins. C) pesticides. D) paper pulping.

D) paper pulping.

3) Which organisms form the foundation of the carbon cycle? A) anaerobic chemolithotrophs B) chemoheterotrophs C) chemoorganotrophs D) phototrophs

D) phototrophs

18) Ocean acidification decreases the precipitation of calcium carbonate and thus will probably affect the cycling of Ca and other nutrients in the ocean.

True

19) Mercury has both organic and inorganic forms that are neurotoxic.

True

2) More carbon is present in dead organic material on Earth than in living organisms.

True

13) Which of the following is a sulfide? A) H2S B) HS- C) S2- D) H2S, HS-, and S2- are all sulfides.

D) H2S, HS-, and S2- are all sulfides.

25) What reaction is catalyzed by mercuric reductase? A) CH3HgCH3 to Hg2+ B) CH3Hg+ to Hg2+ C) Hg4+ to Hg2+ D) Hg2+ to Hg0

D) Hg2+ to Hg0

30) Which statement exemplifies the biological pump concept? A) Autotrophs bring in light photons to synthesize ATP. B) Bacteria oxidize Fe2+ into Fe3+, and Archaea reduce Fe3+ back into Fe2+. C) Calcium ions are brought into cells while toxic physiological byproducts are released. D) Primary producers sink to the deep ocean, which provides deep ocean organisms with nutrients when the primary producers die.

D) Primary producers sink to the deep ocean, which provides deep ocean organisms with nutrients when the primary producers die.

28) The ocean has mitigated the impact of anthropogenic carbon dioxide production by A) absorbing 500 billion tons of atmospheric carbon dioxide. B) absorbing over 80% of the trapped heat energy. C) storing 600 billion tons of organic carbon. D) absorbing 500 billion tons of atmospheric carbon dioxide and over 80% of the trapped heat energy.

D) absorbing 500 billion tons of atmospheric carbon dioxide and over 80% of the trapped heat energy.

34) Which of the following processes does denitrification contribute to? A) acid rain B) ozone depletion C) global warming D) acid rain, ozone depletion, and global warming

D) acid rain, ozone depletion, and global warming

41) Increasing atmospheric carbon dioxide is A) increasing sedimentation of C, Ca, and Si. B) increasing the effect of the biological pump. C) fueling increased primary production in ocean waters. D) acidifying the ocean and decreasing the rate of formation of calcareous shells.

D) acidifying the ocean and decreasing the rate of formation of calcareous shells.

43) Nitrogen fixation results in the A) loss of biologically available N from an ecosystem. B) formation of nitrogen gas. C) direct formation of nitrate. D) addition of biologically available N to an ecosystem.

D) addition of biologically available N to an ecosystem.

33) Lignin is a complex polymer of methoxylated ________ compounds and is present in ________. A) silica / aquatic environments B) mineral / rocks C) oil / fossil fuels D) aromatic / vascular plant material

D) aromatic / vascular plant material

37) Sulfide is toxic to respiring organisms, because it can combine with metals present in ________ that serve a critical function in respiration. A) glycolysis enzymes B) oxidases C) NADH D) cytochromes

D) cytochromes

44) Nitrous oxide (N2O) is a A) product of denitrification. B) product of nitrification. C) potent greenhouse gas. D) potent greenhouse gas that is a product of denitrification.

D) potent greenhouse gas that is a product of denitrification.

19) What is a characteristic of a deep sea marine cold seep/vent? A) acidic B) luminous C) low pressure D) rich in methane

D) rich in methane

12) The burning of fossil fuels produces significant amounts of A) sulfate. B) sulfite. C) sulfonate. D) sulfur dioxide.

D) sulfur dioxide.

5) A process where different microbial taxa work in cooperation to degrade a compound that neither can perform entirely on their own is called A) allotrophy. B) ammensalism. C) commensalism. D) syntrophy.

D) syntrophy.

16) Which iron species is produced primarily from iron smelting and rarely is produced by microbial-mediated processes? A) ferric iron (Fe3+) B) ferrous iron (Fe2+) C) ferrulic iron (Fe1+) D) iron (Fe0)

D) iron (Fe0)

24) Which is the MOST toxic form of mercury? A) CH3Hg+ B) Hg0 C) Hg2+ D) Hg4+

A) CH3Hg+

1) ________ is a term used to describe dead organic matter. A) Humus B) Loam C) Pyrite D) Xenocompost

A) Humus

29) What is the main form of nitrogen found on Earth? A) N2 B) NO C) NO3- D) NH4

A) N2

15) When dimethylsulfoniopropionate (DMSP) is aerobically degraded in a marine environment, which product is most often used to support growth? A) acrylate B) dimethyl disulfide C) dimethyl sulfoxide D) methanethiol

A) acrylate

47) Human activities have disrupted the carbon cycle by A) burning carbon stored as fossil fuels or biomass, thus increasing the amount of carbon dioxide in the atmosphere. B) decreasing the primary productivity of the oceans, resulting in increased atmospheric carbon dioxide. C) burning methane hydrates to produce electricity. D) acidifying the ocean, resulting in the release of large amounts of dissolved carbon dioxide into the atmosphere.

A) burning carbon stored as fossil fuels or biomass, thus increasing the amount of carbon dioxide in the atmosphere.

20) The Ca cycle is tightly coupled to the A) carbon cycle through calcium carbonate formation in ocean waters. B) phosphorus cycle through calcium phosphate formation in sediments and rocks. C) silica cycle through calcium silicate formation in coastal ocean sediments. D) nitrogen cycle because nitrogenase requires calcium ions.

A) carbon cycle through calcium carbonate formation in ocean waters.

38) Lysis of marine algae and cyanobacteria releases the major osmoregulatory solute, dimethylsulfoniopropionate (DMSP), which is degraded into the most abundant organic S compound in nature, ________. A) dimethyl sulfide (CH3-S-CH3) B) hydrogen sulfide (H2S) C) gypsum (CaSO4) D) elemental sulfur (So)

A) dimethyl sulfide (CH3-S-CH3)

42) Studying the redox cycling of Fe in the environment has led to the discovery A) of bacteria that transfer electrons long distances and generate electric currents. B) of bacteria that destroy toxic metal ions. C) of archaea that have Fe in their cell walls. D) that Fe limits primary production in terrestrial ecosystems.

A) of bacteria that transfer electrons long distances and generate electric currents.

21) Phosphorus reservoirs include A) phosphate minerals in rocks, dissolved phosphates in aquatic environments, and the nucleic acids and phospholipids of living organisms. B) mineral phosphonates and the nucleic acids and phospholipids of living organisms. C) elemental phosphorus minerals and phosphonates. D) elemental phosphorous, polyphosphate, and phosphonates.

A) phosphate minerals in rocks, dissolved phosphates in aquatic environments, and the nucleic acids and phospholipids of living organisms.

22) The Fe and Mn cycles include A) reduced and oxidized forms that are very chemically reactive. B) large reservoirs of solid mineral forms that are chemically inert. C) incorporation of Fe and Mn into the exoskeletons of diatoms and other alga. D) toxic forms that can poison aquatic ecosystems if the cycles are imbalanced.

A) reduced and oxidized forms that are very chemically reactive.

27) Greenhouse gases A) such as CO2, CH4, and N2O trap infrared radiation and heat the Earth. B) such as CO2 increase plant and animal growth, resulting in more heat production on Earth. C) such as CO2 and O3 (ozone) interact with UV light and heat the Earth. D) such as CO2, CH4, and N2O destroy O3 (ozone) and allow more UV light to enter the atmosphere, thus increasing the temperature of the Earth's surface.

A) such as CO2, CH4, and N2O trap infrared radiation and heat the Earth.

32) The largest reservoir of methane is found A) trapped under permafrost and marine sediments. B) in the rumen of cows and other ruminant animals. C) in the atmosphere. D) trapped in volcanic rocks.

A) trapped under permafrost and marine sediments.

7) One important difference between the C, N, and S cycles and the P, Ca, and Si cycles is that A) P, Ca, and Si are NOT cycled in terrestrial environments. B) the P, Ca, and Si cycles do NOT involve redox changes or gaseous forms that can alter Earth's atmospheric chemistry. C) the P, Ca, and Si cycles do NOT involve microbial activity. D) the P, Ca, and Si cycles are NOT affected by global warming or other human activity.

B) the P, Ca, and Si cycles do NOT involve redox changes or gaseous forms that can alter Earth's atmospheric chemistry.

40) Coccolithophores and foraminiferans both use ________ to form their exoskeletons. A) Si4+ B) Fe3+ C) Ca2+ D) HPO4-

C) Ca2+

46) The oxidation of ________ occurs both biotically and abiotically; however, at ________ pH values biotic oxidation is more common. A) Si / low B) ammonia / high C) Fe2+ / low D) Hgo / low

C) Fe2+ / low

26) Agricultural application of nitrogen fertilizer A) reduces global warming by increasing the storage of carbon dioxide in plant biomass. B) increases global warming by increasing microbial respiration in agricultural soils. C) increases global warming by increasing the production of nitrous oxide (N2O) by denitrification in agricultural soils. D) has little to no effect on the carbon cycle.

C) increases global warming by increasing the production of nitrous oxide (N2O) by denitrification in agricultural soils.

17) Bacterial oxidation of Fe2+ occurs BEST under which environmental condition? A) cold temperature B) high sunlight C) low (acidic) pH D) nutrient-replete

C) low (acidic) pH

11) Which compound in fertilizer do farmers use to inhibit the production of easily leached nitrogen compounds? A) anhydrous ammonia B) carbonate C) nitrapyrin D) nitrate

C) nitrapyrin

18) Diatoms require silicon due to their A) Ca2+/Si4+ symporters. B) DNA replication mechanism. C) ornate frustules. D) unique phototrophic physiology.

C) ornate frustules.

2) Which of the following is/are NOT a degradation product of organic material? A) carbon dioxide B) methane C) oxygen D) carbon dioxide, methane, and oxygen

C) oxygen

14) What would the result be when a soil is supplemented with S0? A) dimethyl sulfide production due to mixotrophs B) organic carbon production due to anaerobes C) soil acidification due to chemolithotrophs D) syntrophic utilization of sulfite

C) soil acidification due to chemolithotrophs

36) In the oceans, sulfur exists primarily as ________, and in rocks and sediments sulfur occurs mostly as ________ and ________. A) hydrogen sulfide (H2S) / gypsum (CaSO4) / elemental sulfur (So) B) hydrogen sulfide (H2S) / sulfate (SO42-) / elemental sulfur (So) C) sulfate (SO42-) / gypsum (CaSO4) / pyrite (FeS2) D) sulfate (SO42-) / sulfide (H2S) / elemental sulfur (So)

C) sulfate (SO42-) / gypsum (CaSO4) / pyrite (FeS2)

1) In the natural carbon cycle, carbon dioxide is returned to the atmosphere by the respiration of animals and chemoorganotrophic microorganisms.

True

10) The disposal of garbage or sewage in the ocean is known to cause the sudden growth of sulfate reducers.

True

11) Most chemolithotrophic bacteria that oxidize sulfur are aerobes.

True

13) Abiotic oxidation of Fe2+ requires oxygen; no other chemicals can directly oxidize Fe2+.

True

15) Most phosphorous, such as that found in inorganic phosphate (HPO4-), exist in the +5 oxidation state in nature.

True

21) Some bacteria have genes that confer resistance to mercury.

True

22) Mercury can serve as a transcriptional activator in the regulation of certain genes.

True

24) Mercury-resistant bacteria detoxify mercury by producing Hg0.

True

27) The two main biological activities in the Ca and Si cycles are the biosynthesis of shells and exoskeletal material as well as the mineralization of these materials in sediments.

True

5) In a global sense, ALL nutrient cycles are coupled together.

True

7) Syntrophic organisms cannot grow fermentatively without a hydrogen-consuming partner organism.

True

8) Acetogens can ferment glucose into acetate, but methanogens cannot.

True