CH15

1) Microbial diversity is thought of in terms of phylogenetic diversity and functional diversity because A) similar functional traits are often found in divergent phylogenetic groups. B) phylogenetic diversity dictates functional diversity in microbes. C) functional diversity only pertains to functions that are not phylogenetic. D) similar phylogenetic groups almost always have similar functional traits.

A) similar functional traits are often found in divergent phylogenetic groups.

3) What form of photosynthesis evolved first on Earth? A) Oxygenic B) Anoxygenic C) Autotrophic D) Heterotrophic

B) Anoxygenic

32) In which of the following environments would you expect to find a high number of iron-reducing bacteria? A) Acidic mine drainage B) Deep subsurface C) Open ocean D) Agriculture soil

B) Deep subsurface

13) Green nonsulfur bacteria are a ________ that are found in ________ environments. A) monophyletic group / anoxic B) polyphyletic group / oxic C) morphologically distinct group / anoxic D) morphologically distinct group / oxic

A) monophyletic group / anoxic

16) The vacuole of the giant sulfide-oxidizing bacterium Thiomargarita namibiensis contains ________ that is used to oxidize hydrogen sulfide under ________ conditions. A) nitrate / anoxic B) sulfate / anoxic C) oxygen / oxic D) sulfur / anoxic

A) nitrate / anoxic

23) Thioploca species contain large vacuoles that store ________, which is used to ________ under anaerobic conditions. A) nitrate / oxidize sulfide B) oxygen / oxidize sulfur C) sulfur / reduce nitrate D) glycogen / provide energy

A) nitrate / oxidize sulfide

39) Epibiotic predators A) obtain nutrients by attaching to the surface of prey. B) invade the cytoplasm of their prey. C) invade the periplasmic space of their prey. D) find prey using swarming behavior.

A) obtain nutrients by attaching to the surface of prey.

19) The Cyanobacteria are united by their ________, but their ________ is very diverse. A) physiology / morphology B) morphology / physiology C) ecology / physiology D) SSU rRNA gene sequences / physiology

A) physiology / morphology

30) Which of the following traits do ammonia and nitrite oxidizers share? A) Chemoorganotrophic B) Autotrophic C) Aerobic D) Autotrophic and aerobic

D) Autotrophic and aerobic

11) You are looking at a sample from the top green layer of a colorful bacterial mat. Using phase contrast and fluorescence microscopy, you see evenly spaced cells in the middle of a filament that are slightly smaller than the others. The smaller cells are not fluorescent, indicating they lack photosystem II, but the rest of the filament is fluorescent. What type of filamentous bacteria are you most likely looking at? A) Purple nonsulfur bacteria B) Green sulfur bacteria C) Acidobacteria D) Cyanobacteria

D) Cyanobacteria

38) Which of the following functional groups form symbiotic relationships with Eukaryotes in deep sea environments? A) Dissimilatory iron-oxidizers B) Methanotrophs C) Sulfide-oxidizers D) Methanotrophs and sulfide-oxidizers

D) Methanotrophs and sulfide-oxidizers

15) Considering the relationship between oxidizers and reducers, which of the following pairs of microorganisms are NOT likely to form close associations or consortia? A) Purple sulfur bacteria and dissimilative sulfur-reducers B) Dissimilative sulfur-reducers and dissimilative sulfur-oxidizers C) Diazotrophs and fungi D) Nitrogen-fixing cyanobacteria and dissimilative sulfate-reducers

D) Nitrogen-fixing cyanobacteria and dissimilative sulfate-reducers

7) Aerobic anoxygenic phototrophs A) do not use bacteriochlorophyll. B) are an ancient monophyletic group of bacteria. C) can be either autotrophic or heterotrophic. D) cannot fix CO2.

D) cannot fix CO2.

28) What growth conditions would you use to enrich for ammonia-oxidizing bacteria? A) Aerobic mineral media with ammonia and bicarbonate incubated in the dark B) Anaerobic mineral media with acetate and ammonia incubated in the dark C) Aerobic mineral media with acetate and ammonia incubated in the dark D) Anaerobic mineral media with ammonia and nitrate incubated in the dark

A) Aerobic mineral media with ammonia and bicarbonate incubated in the dark

33) Which of the following functional groups would you expect to find in aerobic iron- and sulfur-rich acidic mine drainage? A) Dissimilative iron-oxidizers B) Dissimilative iron-reducers C) Purple sulfur bacteria D) Purple sulfur bacteria and dissimilative iron-reducers

A) Dissimilative iron-oxidizers

35) What microbes have a symbiotic association with mussels, living in their gill tissue? A) Methanotrophs B) Iron-oxidizing bacteria C) Bioluminescent bacteria D) Sulfur oxidizing bacteria

A) Methanotrophs

9) Which group of bacteria would you expect to find in a shallow clear hot spring with high concentrations of geochemically produced hydrogen sulfide? A) Purple sulfur bacteria B) Single-celled Cyanobacteria C) Dissimulative sulfate-reducing bacteria D) Symbiotic diazotrophs

A) Purple sulfur bacteria

37) Most methanotrophs are obligate ________ because ________. A) aerobes / the initial step of methane oxidation requires O2 B) anaerobes / methane is produced in anaerobic environments C) fermenters / methane only provides enough energy for fermentation D) heterotrophs / methane does not provide enough carbon for growth

A) aerobes / the initial step of methane oxidation requires O2

36) What is the difference between a methylotroph and methanotroph? A) Methylotrophs are strict anaerobes, while methanotrophs are strict aerobes. B) Methylotrophs use organic carbon lacking C-C bonds as electron donors and carbon sources, while methanotrophs exclusively use methane as an electron donor and carbon source. C) Methylotrophs produce organic carbon lacking C-C bonds, while methanotrophs exclusively produce methane. D) Methylotrophs are in Proteobacteria, while methanotrophs are in Archaea.

B) Methylotrophs use organic carbon lacking C-C bonds as electron donors and carbon sources, while methanotrophs exclusively use methane as an electron donor and carbon source.

12) You are looking at a sample from the top green layer of a colorful bacterial mat. Using phase contrast and fluorescence microscopy, you see evenly spaced cells in the middle of a filament that are slightly smaller than the others. The smaller cells are not fluorescent, indicating they lack photosystem II, but the rest of the filament is fluorescent. What is the most likely function of the smaller cells in the filament? A) Survival in the dark B) Nitrogen fixation C) Sulfur storage D) Nitrate storage

B) Nitrogen fixation

34) What is one especially unique characteristic of methanotrophs? A) They metabolize H2S. B) They have unusually large amounts of sterols. C) They can exist as consortia. D) They are capable of bioluminescence.

B) They have unusually large amounts of sterols.

10) The ecological diversity of phototrophic bacteria is illustrated by the different ________ that allow them to perform photosynthesis in low light environments such as deep in the ocean, in various sediments, and in thick layered mats. A) nitrogen fixation strategies B) bacteriochlorophyll and photosystems C) specialized stalked cells D) endospores and resistant cell types

B) bacteriochlorophyll and photosystems

20) Purple sulfur bacteria are A) alphaproteobacteria that oxidize hydrogen sulfide in the presence of oxygen or nitrate. B) gammaproteobacteria that use hydrogen sulfide as an electron donor for photosynthesis. C) a phylogenetically heterogeneous group of microbes that reduce sulfate to sulfur. D) thermophilic bacteria that reduce elemental sulfur to sulfide.

B) gammaproteobacteria that use hydrogen sulfide as an electron donor for photosynthesis.

14) Typical electron donors used by dissimilative sulfate-reducers are A) hydrogen, water, and hydrogen sulfide. B) hydrogen, lactate, and pyruvate. C) carbon dioxide, hydrogen, and water. D) sulfate, sulfur, and thiosulfate.

B) hydrogen, lactate, and pyruvate.

22) Dissimilative sulfide-oxidizers use a variety of unique ecological strategies in order to A) avoid the toxicity of hydrogen sulfide. B) position themselves at interfaces where sulfide and oxygen meet. C) position themselves where there is sufficient light for sulfide oxidation. D) find organic carbon substrates.

B) position themselves at interfaces where sulfide and oxygen meet.

17) Nitrogen fixation is A) rare among microorganisms. B) widespread among microorganisms. C) limited to Proteobacteria. D) common in Bacteria, but absent in Archaea.

B) widespread among microorganisms.

6) Which of the following conditions would you use to enrich purple nonsulfur bacteria from lake sediments? A) Anoxic media with a good light source B) Mineral media with ammonia and oxygen in the dark C) Anoxic mineral media with an organic acid and a good light source D) Mineral media with nitrate and acetate in the dark

C) Anoxic mineral media with an organic acid and a good light source

4) The only group of oxygenic phototrophic bacteria are the A) green nonsulfur bacteria. B) Chloroflexi. C) Cyanobacteria. D) Chlorobi.

C) Cyanobacteria.

29) Escherichia coli is a chemoorganotrophic, facultative aerobe and belongs to the phylum Proteobacteria. Based on this information, which of the following functional groups does E. coli most likely belong to? A) Green sulfur bacteria B) Ammonia-oxidizing bacteria C) Denitrifying bacteria D) Nitrite-oxidizing bacteria

C) Denitrifying bacteria

31) Dissimilative iron-reducing bacteria couple which oxidation-reduction reactions? A) The reduction of ferric iron or manganese and the oxidation of sulfur. B) The reduction of ferric iron or manganese and the fermentation of sugars. C) The oxidation of H2 or organic compounds and the reduction of ferric iron or manganese. D) The reduction of ferric iron and photosynthesis.

C) The oxidation of H2 or organic compounds and the reduction of ferric iron or manganese.

24) In symbiotic associations between sulfur chemolithotrophs and eukaryotes, such as tube worms and giant clams, the bacterial symbiont provides ________ while the host provides ________. A) nitrogen / carbon and oxygen B) sulfide / oxygen C) a carbon and energy source / stable sulfide and oxygen levels D) organic acids / stable sulfate levels

C) a carbon and energy source / stable sulfide and oxygen levels

8) Aside from using light as a source of energy, another important part of the functional diversity of some bacterial phototrophs is their A) capacity for bioluminescence. B) ability to form prosthecate and stalked cells. C) ability to fix nitrogen gas. D) ability to degrade neurotoxins.

C) ability to fix nitrogen gas.

25) The Bacteria and Archaea are the only domains in which organisms exist that can A) catalyze the transformation of inorganic nitrogen species for biosynthesis. B) assimilate nitrite. C) conserve energy from the transformation of inorganic nitrogen species. D) catalyze the incorporation of inorganic nitrogen species into biomolecules.

C) conserve energy from the transformation of inorganic nitrogen species.

26) Nitrogenase is a critical enzyme in the nitrogen cycle because it catalyzes the A) assimilation of ammonia. B) dissimilative reduction of nitrate to nitrogen gas. C) fixation of nitrogen gas into ammonia. D) oxidation of nitrogen gas into nitrate.

C) fixation of nitrogen gas into ammonia.

18) The phylogenetic trees of the nifH and SSU rRNA genes of nitrogen-fixing bacteria are incongruent because A) nitrogenase is an anaerobic enzyme. B) this is a characteristic of all enzyme genes. C) of horizontal gene transfer. D) very few microbes have the nifH gene.

C) of horizontal gene transfer.

40) Bdellovibrio species are ________ cells that replicate in the ________. A) symbiotic / gills of clams B) lithotrophic / deep subsurface C) predatory / periplasmic space D) denitrifying / sediments of freshwater lakes

C) predatory / periplasmic space

2) Functional traits can be shared between organisms with divergent SSU rRNA gene sequences because A) functional traits may be lost by different lineages over time. B) functional traits may evolve independently in different lineages over time. C) horizontal gene transfer can result in the transfer of genes between divergent lineages. D) functional traits may evolve independently, be shared through horizontal gene transfer, or be lost in divergent lineages.

D) functional traits may evolve independently, be shared through horizontal gene transfer, or be lost in divergent lineages.

21) Green sulfur bacteria are often found at the greatest depths of all phototrophic cells in lakes, oceans, and microbial mats. This is because green sulfur bacteria A) are very sensitive to UV irradiation, despite their reliance on light for energy. B) are the only phototrophs that can use hydrogen sulfide as an electron donor for photosynthesis. C) are strict anaerobes. D) have chlorosomes that are very efficient at harvesting light, allowing them to perform photosynthesis where light intensities are very low.

D) have chlorosomes that are very efficient at harvesting light, allowing them to perform photosynthesis where light intensities are very low.

42) Prosthecae are an adaptation for A) anaerobic growth. B) cell differentiation under harsh conditions. C) nitrogen fixation. D) low nutrient aquatic environments.

D) low nutrient aquatic environments.

27) Diazotrophs maximize nitrogenase activity by A) closely coupling N2 fixation with high rates of photosynthesis. B) fixing N2 at times when oxygen is absent or in low concentrations. C) producing specialized structures to protect nitrogenase from oxygen. D) producing specialized structures or fixing N2 at times when oxygen is absent to protect nitrogenase from oxygen.

D) producing specialized structures or fixing N2 at times when oxygen is absent to protect nitrogenase from oxygen.

41) Myxobacteria display ________ behavior and form ________ that produce myxospores. A) gliding / slime trails B) chemotactic / colonies C) phototactic / slime trails D) swarming / fruiting bodies

D) swarming / fruiting bodies

5) All microbial phototrophs A) fix carbon dioxide. B) use water as an electron donor for photosynthesis. C) fix carbon dioxide and use water as an electron donor for photosynthesis. D) use light energy to drive electron transport to generate energy.

D) use light energy to drive electron transport to generate energy.