MicroBiology Chapter 21

26) Which is the most toxic form of mercury in animals? A) CH3Hg+ B) Hg0 C) Hg2+ D) Hg4+

A) CH3Hg+

37) 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.

18) Under which condition is ferrous iron (Fe2+) not spontaneously oxidized? A) Neutral pH B) Acidic pH C) Iron rich D) Manganese rich

B) Acidic pH

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

B) produces

15) What is the primary product when dimethylsulfoniopropionate (DMSP) is aerobically degraded in a marine environment? A) Acrylate B) Dimethyl disulfide C) Dimethyl sulfoxide D) Methanethiol

B) Dimethyl disulfide

33) What is the largest carbon reservoir on Earth? A) Terrestrial biosphere B) Rocks and sediments C) Aquatic biosphere D) Fossil fuels

B) Rocks and sediments

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 reduced into ammonia to produce energy for the cell is called A) ammonification. B) dissimilative reduction of nitrate to ammonia (DRNA). C) denitrification. D) the anammox reaction.

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

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

B) organic

39) 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

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

D) methane hydrates.

46) Nitrous oxide (N2O) is a A) direct product of ammonification. B) direct product of nitrogen fixation. C) potent greenhouse gas that is a product of nitrification. D) potent greenhouse gas that is a product of denitrification.

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

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

D) reduces NO3-.

25) Mercury is commonly found in A) some electronics, but not in pesticides. B) some compounds that are neurotoxins, but not in electronics. C) some pesticides, but not in any neurotoxins. D) some electronics, some pesticides, and some neurotoxic compounds.

D) some electronics, some pesticides, and some neurotoxic compounds.

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 degrade entirely on their own is called A) allotropy. B) amensalism. C) commensalism. D) syntrophy.

D) syntrophy.

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

A) Humus

31) What is the major reservoir of stable nitrogen? A) N2 B) NO C) NO3- D) NH4

A) N2

17) How does Pseudomonas aeruginosa transfer electrons extracellularly to reduce iron? A) Pyocyanin B) Humic substances C) Pili D) Flavin mononucleotide (FMN)

A) Pyocyanin

34) The largest reservoir of methane is found A) as methane hydrates trapped under permafrost and marine sediments. B) in the rumen of cows and other ruminant animals. C) in the atmosphere in gaseous form. D) trapped in volcanic rocks in tropical environments around the world.

A) as methane hydrates trapped under permafrost and marine sediments.

49) 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.

22) The calcium 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.

40) Lysis of marine algae and cyanobacteria releases a 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 (S0).

A) dimethyl sulfide (CH3-S-CH3).

44) Studying the redox cycling of Fe in the environment has led to the discovery A) of bacteria that transfer electrons as a form of electricity. 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 as a form of electricity.

23) 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 phosphorus, polyphosphate, and phosphonates.

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

24) 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.

29) The greenhouse effect is caused by gases A) such as CO2, CH4, and N2O that trap infrared radiation, heating the Earth. B) such as CO2 that increase plant and animal growth, resulting in more heat production on Earth. C) such as CO2 and O3 (ozone) that interact with UV light and heat the Earth. D) such as CO2, CH4, and N2O that 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 that trap infrared radiation, heating the Earth.

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

B) oxidize ammonia, but nitrification uses O2 as an electron acceptor and anammox uses NO2-.

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.

42) Coccolithophores and foraminiferans both use ________ to form their exoskeletons. A) Si4+ B) Fe3+ C) Ca2+ D) HPO42-

C) Ca2+

48) The oxidation of ________ occurs both biotically and abiotically, but biotic oxidation is more common at ________ pH values. A) Si / low B) ammonia / high C) Fe2+ / low D) Hg0 / low

C) Fe2+ / low

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

2) Which of the following is/are NOT a degradation product of organic material? A) Carbon dioxide B) Methane C) Oxygen D) All of these answer choices are degradation products of organic material.

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

28) 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.

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

C) ornate frustules.

19) Bacterial oxidation of Fe2+ is commonly studied in chemolithotrophs that thrive under which specific environmental condition? A) Cold temperature B) High sunlight C) pH D) Nutrient replete

C) pH

38) In the oceans, sulfur exists primarily as A) hydrogen sulfide (H2S). B) elemental sulfur (S0). C) sulfate (SO42-). D) gypsum (CaSO4).

C) sulfate (SO42-).

36) 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

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.

27) What reaction is catalyzed by mercuric reductase? A) Hg(CH3)2 to Hg2+ B) CH3Hg+ to Hg2+ C) Hg4+ to Hg2+ D) Hg2+ to Hg0

D) Hg2+ to Hg0

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) Ferulic iron (Fe1+) D) Iron (Fe0)

D) Iron (Fe0)

3) Which organisms form the foundation of the carbon cycle? A) Anaerobic chemolithotrophs B) Chemoheterotrophs C) Chemoorganotrophs D) Phototrophs

D) Phototrophs

32) 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 by-products 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.

21) 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

30) 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.

43) 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.

45) 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.

35) 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