Q&A Hero

Q: 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.

Q: 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.

Q: 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.

Q: 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.

Q: 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.

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

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

Q: 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)

Q: 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

Q: 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)

Q: 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.

Q: 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

Q: 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

Q: 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.

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

Q: 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.

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

Q: 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.

Q: 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.

Q: 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.

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

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

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

Q: 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.

Q: 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.

Q: 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.

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

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

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

Q: 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)

Q: 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

Q: 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

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

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

Q: 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

Q: 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.

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

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

Q: 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.

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

Q: 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.

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

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

Q: 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

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

Q: ________ are the main primary producers in freshwater environments. A) Phototrophic microorganisms B) Heterotrophic microorganisms C) Chemolithotrophic microorganisms D) Viral microorganisms

Q: The number of Roseobacter in the ocean describes A) species diversity. B) species richness. C) species abundance. D) species prevalence.

Q: Sedimentation in bogs and marshes develop ________ soils. A) inorganic B) mineral C) organic D) loamy

Q: Which of the following an example of a biofilm? A) soap scum B) dental plaque C) marine diatom D) planktonic microcolony

Q: A population of metabolically related microorganisms is called a(n) A) guild. B) niche. C) ecosystem. D) haplotype.

Q: Ecological theory states that for every organism there is at LEAST one ________, and the microenvironment where the organism is MOST successful is called the ________. A) population / community B) niche / prime niche C) prime niche / niche D) community / population

Q: A chemical that comes from outside the ecosystem is referred to as a(n) ________ chemical. A) synthropic B) lithotrophic C) allochthonous D) pleomorphic

Q: What adaptation do organisms have that tolerate high pressures? A) decreased cell size B) decreased lipid content C) increased ribosome size D) increased unsaturated fatty acids

Q: The primary metal sulfides emitted from the black smokers are ________ sulfides. A) copper B) iron C) magnesium D) zinc

Q: Which statement is TRUE about the fluid from the hydrothermal vents? A) The fluid contains large amounts of oxidized inorganic materials. B) The fluid contains large amounts of reduced inorganic materials. C) The fluid contains large amounts of organic material. D) The fluid usually contains about equal amounts of organic and inorganic material.

Q: Shallow marine sediments are dominated by A) Firmicutes. B) Planctomycetes. C) Proteobacteria. D) Tenericutes.

Q: Archaea in pelagic deep-water are almost exclusively A) Crenarchaeota. B) Euryarchaeota. C) Nanoarchaeota. D) Thaumarchaeota.

Q: Epsilonproteobacteria are most dominant in hydrothermal vents because they A) reduce nitrogen. B) oxidize reduced sulfur compounds. C) use oxygen as electron acceptors. D) bind divalent cations.

Q: What is an average concentration of prokaryotic cells along the surface of pelagic water? A) 104 cells/ml B) 106 cells/ml C) 108 cells/ml D) 1010 cells/ml

Q: Which of the following is NOT an oxygenic phototrophic microorganism present in marine waters? A) Ostreococcus B) Prochlorococcus C) Roseobacter D) Trichodesmium

Q: All Prochlorococcus strains contain A) chlorophylls a and b. B) chlorophyll a and phycobilins. C) chlorophyll b and phycobilins. D) chlorophylls a andb and phycobilins.

Q: From the aquatic systems below, where are heterotrophic Bacteria the MOST abundant? A) coastal waters B) deep sea C) Sargasso Sea D) open ocean

Q: Which are the MOST dominant chemolithotrophs in pelagic waters? A) ammonia-oxidizing Archaea B) ammonia-oxidizing Bacteria C) sulfate-reducing Bacteria D) Prochlorococcus

Q: Which aquatic habitat contains a pelagic zone? A) estuary B) lake C) salt marsh D) open ocean

Q: The chemical oxygen demand (COD) of a body of water is determined using a(n) A) microelectrode. B) oxygenator. C) spectrophotometer to determine the OD540nm. D) strong oxidizing agent.

Q: An organism living in the bottommost region of a body of water is described as being A) benthic. B) litoral. C) neritic. D) pelagic.

Q: Which bacterial genus is responsible for producing ferrous iron (Fe2+) in groundwater? A) Alteromonas B) Aquifex C) Geobacter D) Loktanella

Q: According to bacterial abundance studies done so far on soils, the ________ represent the most abundant phylum. A) Proteobacteria B) Acidobacteria C) Actinobacteria D) Firmicutes

Q: A soil that lacks a dominate particle size is referred to as a(n) A) aggregation. B) bisequum. C) loam. D) mottled soil.

Q: Which is the CORRECT order of increasing size in soil particles? A) clay > sand > silt B) clay > silt > sand C) sand > clay > silt D) silt > clay > sand

Q: Assuming exposure to the same climate, which of the following aquatic systems would be MOST stratified? A) 20 m deep freshwater river B) 50 m deep marine water fjord C) 200 m deep saltwater lake D) 300 m deep freshwater lake

Q: During periods of stratification, transfer between surface and bottom waters is controlled by A) mixing. B) diffusion. C) niche partitioning. D) current.

Q: Which metabolic strategy is MOST common in chemolithotrophic mats? A) ammonia oxidation B) iron oxidation C) nitrate reduction D) sulfur oxidation

Q: Which of the following can function as intracellular signaling molecules? A) acylated homoserine lactones B) hydrophilic lipids C) quinones D) proteorhodopsins

Q: The emergence of new microbial species because of geographic isolation is called ________ speciation. A) allopatric B) biogeochemical C) biogeological D) isolatory

Q: Microenvironments of soil exist where ________ concentrations greatly vary. A) oxygen B) nitrate C) sulfur D) oxygen, nitrate, and sulfur

Q: The photosynthetic pigments bacteriorhodopsin and proteorhodopsin are present in ________ and ________, respectively. A) Archaea / Bacteria B) Bacteria / Archaea C) Bacteria / Bacteria D) Bacteria / Eukarya

Q: In a stratified lake, the warmer and less dense layer is called the A) epilimnion. B) hypolimnion. C) hyperlimnion. D) thermocline.

Q: The generation time of Escherichia coli in the human intestine is ________ in laboratory culture. A) at about the same rate as B) faster than C) more optimal than D) slower than

Q: Some nitrifying prokaryotes carry out metabolic cooperation by a process known as A) competition. B) niche partitioning. C) syntrophy. D) antagonism.