Microbio Ch 28
Which organisms would most likely be present on the bottom or closest to the attachment surface of a complex microbial biofilm? -Eukaryotic protists -Facultative chemoorganotrophs -Cyanobacteria -Anaerobic sulfate-reducing bacteria
Anaerobic sulfate-reducing bacteria
NH4--> N2
Anammox
SO4 --> Organic S
Assimilatory Sulfate Reduction
NO3 --> Organic N
Assimilatory nitrate reduction
Which of the following is not an example of symbiotic nitrogen fixation? -Anabaenea with a water fern -Azotobacter with certain photosynthetic protists -Rhizobium with leguminous plants -Frankia with woody shrubs
Azotobacter with certain photosynthetic protists
Organic N --> NH4
Decay and mineralization
Organic S --> H2S
Decay and mineralization
Which of the following microbes can oxidize ferrous iron while using chlorate or perchlorate as the electron acceptor? -Thiobacillus ferrooxidans -Dechlorosoma suillum -Ferribacterium limneticum -Pseudomonas denitrificans
Dechlorosoma suillum
N2 --> NH3 --> Organic N
N2 fixation
Chemolithoautotrophs use ______ and NO₂- as a source of ___________ and CO₂ as their carbon source, producing organic carbon and ___________ as their metabolic biproducts.
NH₄+ electrons nitrate
Nitrification occurs in
aerobic conditions
Anammox occurs in
anaerobic conditions
Denitrification occurs in
anaerobic conditions
Methanogenesis occurs in
anaerobic conditions
Nitrogen fixation occurs in
anaerobic conditions
Sulfate reduction occurs in
anaerobic conditions
When reviewing the carbon cycle, inorganic carbon (CO2) and organic carbon can be reduced _________. -anaerobically to methane (CH4) -aerobically to methane (CH4) -anaerobically to carbon monoxide (CO) -aerobically to carbon monoxide (CO)
anaerobically to methane (CH4)
Nitrate can be reduced by organisms carrying out ________________ nitrate reduction or returned to the atmosphere as _______ following ________________ by anaerobes. Nitrogen-fixing microbes produce ammonia for incorporation into proteins and nucleic acids, the production of which often dictates the amount of carbon flux in the environment by supporting microbial growth.
assimilatory N₂ denitrification
Biogeochemical cycles are dynamic, interconnected processes that over geological time allow the ___________ to be self-sustaining.
biosphere
Carbon fixation occurs in
both aerobic and anaerobic conditions
Fermentation occurs in
both aerobic and anaerobic conditions
Methane oxidation occurs in
both aerobic and anaerobic conditions
Respiration occurs in
both aerobic and anaerobic conditions
Sulfur oxidation occurs in
both aerobic and anaerobic conditions
The carbon cycle begins with _________. -the conversion of carbon dioxide to methane -carbon dioxide fixation -anaerobic respiration -aerobic respiration
carbon dioxide fixation
Microbes can fix carbon in anoxic environments using anoxygenic photosynthesis as well as by _________. -chemolithoautotrophy in the presence of light -chemolithoautotrophy in the absence of light -chemoorganoautotrophy in the absence of light -chemoorganoautotrophy in the presence of light
chemolithoautotrophy in the absence of light
The oxidized form of inorganic iron that results from microbial oxidative processes is ________. -sulfate iron -nitrate iron -ferric iron -ferrous iron
ferric iron
The reduced __________ form of iron (_______) can be a source of electrons through _____________ iron oxidation.
ferrous Fe²⁺ lithotrophic
Carbon fixation found in -only in bacteria and archaea -found in eukaryotes, bacteria, and archaea
found in eukaryotes, bacteria, and archaea
Fermentation found in -only in bacteria and archaea -found in eukaryotes, bacteria, and archaea
found in eukaryotes, bacteria, and archaea
Respiration found in -only in bacteria and archaea -found in eukaryotes, bacteria, and archaea
found in eukaryotes, bacteria, and archaea
These organisms must oxidize vast amounts of ____________ compounds to generate enough energy to fix CO₂
inorganic
In addition to the carbon, nitrogen, and sulfur cycles, the _______ and manganese cycles are also based on redox reactions.
iron
Anammox found in -only in bacteria and archaea -found in eukaryotes, bacteria, and archaea
only in bacteria and archaea
Denitrification found in -only in bacteria and archaea -found in eukaryotes, bacteria, and archaea
only in bacteria and archaea
Methane Oxidation found in -only in bacteria and archaea -found in eukaryotes, bacteria, and archaea
only in bacteria and archaea
Methanogenesis found in -only in bacteria and archaea -found in eukaryotes, bacteria, and archaea
only in bacteria and archaea
Nitrification found in -only in bacteria and archaea -found in eukaryotes, bacteria, and archaea
only in bacteria and archaea
Nitrogen fixation found in -only in bacteria and archaea -found in eukaryotes, bacteria, and archaea
only in bacteria and archaea
Sulfate Reduction found in -only in bacteria and archaea -found in eukaryotes, bacteria, and archaea
only in bacteria and archaea
Sulfur Oxidation found in -only in bacteria and archaea -found in eukaryotes, bacteria, and archaea
only in bacteria and archaea
Because of the high requirement for reducing power in nitrogen fixation, the nitrogenase enzyme that carries out the reaction is very sensitive to the presence of _________. -light -carbon dioxide -oxygen -None of the choices are correct.
oxygen
Other biogeochemical cycles do not involve redox transformations such as the ____________ cycle.
phosphorus
Biomagnification involves compounds having higher relative concentrations in _________. -top consumers -lower trophic levels -higher trophic levels -top consumers or higher trophic levels
top consumers or higher trophic levels
Organic matter --> CO2 type and name
Oxidative and redox neutral Respiration and fermentation
Methanogenesis include
-acetate, formate, or H2 + CO2, supply carbon and electrons -strict anaerobes -product is CH4 -anaerobic respiration -methanogens
Methano- and methylotrophy include
-aerobic bacteria -anaerobic archaea -single carbon molecules such as methane and formate supply carbon and electrons -product is CO2
Aerobic oxidation of organic carbon include
-aerobic respiration -chemoorganoheterotrophs -product is CO2
Anaerobic oxidation of organic carbon include
-chemoorganoheterotrophs -product is CO2 -anaerobic respiration -fermentation
Evaluate the environments below and select those that are capable of sustaining methanogenesis. -human oral cavity -marshes -sewage treatment plants -rice paddies -refrigerator -freshwater stream -coal mines -landfills -laboratory incubator -ruminant gut
-marshes -sewage treatment plants -rice paddies -coal mines -landfills -ruminant gut
Biological nitrogen fixation is carried out _________. -only by a limited number of prokaryotes -by prokaryotes and some protists -only by prokaryotes in symbiotic relationships with plants -only in totally anaerobic environments
-only by a limited number of prokaryotes
CO2 fixation include
-oxygenic photosynthesis -photolithoautotrophs -anoxygenic photosynthesis -chemolithoautotrophs -product is a organix carbon
Degradation of organic matter is influenced by _________. -nutrient availability -abiotic conditions -the nature of the microbial community present -All of the choices are correct.
All of the choices are correct.
In the anammox reaction _________. -anaerobic oxidation of ammonia is coupled to the reduction of nitrite -nitrogen gas is evolved -all reactions must take place in the absence of O2 -All of the choices are correct.
All of the choices are correct.
You are performing an experiment in which you have three different incubation chambers: Chamber 1: Aerobic chemoorganotrophic bacteria that use aerobic respiration. Chamber 2: Anaerobic chemoorganotrophic bacteria that use anaerobic respiration. Chamber 3: Anaerobic chemoorganotrophic bacteria that use fermentation. Each chamber has the same concentration or organic carbon. You have added nitrate and phosphate (at a ratio of about 16:1) to each as well as organic molecules to provide a source of other elements. Which chamber do you predict will most likely become nitrate limited (i.e., run out of nitrate) first and which will most likely run out of phosphorus first? -Chamber 1 will run out of nitrate first and chamber 2 will run out phosphate first. -Chamber 2 will run out of nitrate first and chamber 3 will run out phosphate first. -Chamber 1 will run out of nitrate first and chamber 3 will run out phosphate first. -Chamber 2 will run out of nitrate first and chamber 1 will run out phosphate first.
Chamber 2 will run out of nitrate first and chamber 1 will run out phosphate first.
Which of the following does not contribute to the increasing levels of methane in the atmosphere? -Methane production beneath an aerobic water column -Methane production at sewage treatment plants -Methane production in rice paddies -Methane production in termites
Methane production beneath an aerobic water column
NH4 --> NO2 --> NO3
Nitrification (Nitrobacter, Nitrococcus)
All of the following statements concerning nitrogen fixation are true EXCEPT which one? -The products of nitrogen fixation are incorporated into amino acids and nucleic acids. -Nitrogen fixing microbes convert N2 to ammonia. -The amount of carbon that is taken up by plants and microbes can be dictated by how much nitrogen is available to support growth. -Nitrogen fixation does not affect the rate of carbon flux.
Nitrogen fixation does not affect the rate of carbon flux.
Carbon Monoxide occurs in
Occurs in aerobic conditions
From CH4 --> CO2 type and name
Oxidative Methano- and methylotrophy
CO2 --> organic matter type and name
Reductive Co2 fixation photo and chemoautotrophy
NO3 --> N2
denitrification
When nitrate is reduced to dinitrogen gas (N2), nitrogen is removed from the ecosystem and returned to the atmosphere through a series of reactions collectively known as _________. -nitrogen fixation -denitrification -anammox reaction -All of the choices are correct.
denitrification
NO3 --> N2O
dissimilatory nitrate reduction
NO3 --> NO2
dissimilatory nitrate reduction
S2O3 --> H2S
dissimilatory sulfate reduction
SO4 --> S --> H2S
dissimilatory sulfate reduction
In the iron cycle, the oxidized _________ form of iron (_______) can be used as the terminal electron acceptor for anaerobic respiration through ____________ iron reduction.
ferric Fe³⁺ dissimilatory
Peat bogs occur in flooded areas because the rate of decomposition of _________ is slower under anaerobic conditions. -lipids -lignin -protein -starch
lignin
Similarly, in the manganese cycle, some microbes use oxidized ____________ ions in _________ as a terminal electron acceptor for anaerobic respiration and reduced _____________ ions (_______) as a source of electrons.
manganic MnO₂ manganous Mn²⁺
The nitrogen and carbon cycles are linked by microorganisms having different _____________ strategies to create balance in an ecosystem.
metabolic
A major fully reduced form of carbon, important in biogeochemical cycling is _________. methane carbohydrate carbon dioxide hydrogen sulfide
methane
Microbes sometimes make metals such as mercury more volatile and lipid soluble by _________. phosphorylation aggregation methylation None of the choices are correct.
methylation
The release of excess nitrogen into the environment when certain complex organic substrates are used to make new microbial biomass is called __________. nitrification dissimilation denitrification mineralization
mineralization
Phosphorus from organic matter can be _____________ to PO₄ and then _____________ to an organic form.
mineralized immobilized
The process of denitrification involves the transformation of _________. -ammonia to organic matter nitrogen -ammonia to nitrate -nitrate to nitrogen gas -nitrogen gas to ammonia
nitrate to nitrogen gas
The process of nitrogen fixation involves the transformation of _________. -nitrate to nitrogen gas -nitrogen gas to ammonia -ammonia to organic matter nitrogen -ammonia to nitrate
nitrogen gas to ammonia
CO2 --> CH4 type and name
reductive methanogenesis
H2S --> S
sulfide oxidation: hydrogen sulfide serves as electron donor
S --> S2O3
sulfur oxidation: elemental sulfur serves as electron donor
