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Budding bacteria form new cell wall material at a single point rather than throughout the whole cell.

A) True
B) False

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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

E) B) and D)
F) B) and C)

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Dissimilatory nitrate reduction results in the production of gaseous products,while assimilatory nitrate reduction results in the production of ammonia for biosynthesis.

A) True
B) False

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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

E) B) and D)
F) B) and C)

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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) nitrogen-fixing cyanobacteria and fungi
D) nitrogen-fixing cyanobacteria and dissimilative sulfate-reducers

E) A) and C)
F) B) and C)

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The phylogenetic trees of the nifH and SSU rRNA genes are incongruent because


A) nitrogenase is an anaerobic enzyme.
B) nitrogenase evolves rapidly.
C) of horizontal gene transfer.
D) very few microbes have the nifH gene.

E) None of the above
F) B) and C)

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Escherichia coli is a chemoorganotrophic,facultative aerobe and belongs to the Proteobacteria phylum.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

E) C) and D)
F) B) and D)

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Acetogens are anaerobic organisms that produce acetate as the main product of their metabolism.They are important in


A) the production of vinegar.
B) the carbohydrate metabolism of the human gut.
C) hydrothermal vent communities.
D) the production of vitamin C.

E) None of the above
F) A) and D)

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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.

E) B) and C)
F) A) and C)

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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

E) B) and D)
F) C) and D)

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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

E) A) and C)
F) None of the above

Correct Answer

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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

E) A) and B)
F) None of the above

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Although Cyanobacteria contribute more than 35% of all photosynthesis on Earth,they are not visible in the natural environment.

A) True
B) False

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Iron-reducing bacteria are obligately aerobic organisms that reduce ferric iron and oxidize hydrogen or organic compounds.

A) True
B) False

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Anoxygenic phototrophs


A) may use a variety of electron donors for photosynthesis.
B) are an ancient monophyletic group of bacteria.
C) can be either autotrophic or heterotrophic.
D) can be either autotrophic or heterotrophic and may use a variety of electron donors for photosynthesis.

E) A) and D)
F) B) and C)

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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.

E) All of the above
F) B) and C)

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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.

E) None of the above
F) All of the above

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All phototrophic bacteria use a monophyletic photosystem in photosynthesis,thus there is intense competition for light between different phototrophic bacteria.

A) True
B) False

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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

E) All of the above
F) None of the above

Correct Answer

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Thiobacillus species are acidophilic chemolithotrophs capable of autotrophic growth.They perform the dissimilative oxidation of H₂S,Sᵒ,thiosulfate,or Fe⁺².Diagram or explain how Thiobacillus species obtain carbon and energy for growth and predict what type of environment they would be found in.

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Thiobacillus species obtain carbon for g...

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