Flashcards in Microbial Ecology  Deck (41):
Recall that the bacteria in the chapter openers produced electrically-conductive structures that function like "living electrical cables," allowing the organism to conduct electrons along the length of its filament. Under what conditions would production of electrically conductive structures be favored?
Choose all that apply.
A The organism oxidizes H2 and uses iron oxides as the electron acceptor.
B The organism uses an electron donor and an electron acceptor that are physically separated.
C The organism is a chemolithotroph that oxidizes H2 and reduces CO2 to form CH4.
D The organism is photosynthetic and uses H2O as the electron donor.
E The organism ferments glucose and uses it both for the carbon and the energy source.
The use of nitrate (NO3-) as an electron acceptor with formation of one gaseous end product (N2)
The aerobic process that uses ammonium (NH4+) as an energy source
The use of nitrate (NO3-) as an electron acceptor with formation of multiple gaseous end products (N2, N2O, or NO)
An assimilatory process in which N2 is converted to ammonia (NH3) for incorporation into organic nitrogen-containing
Many organisms, both prokaryotic and eukaryotic, release ammonium (NH4+) from degradation of nitrogen-containing organic materials
release of N from an organic source as ammonia (ammonia produced)
Soluble Fe2+ and Mn2+ to insoluble, and back to soluble
soluble --> diffuses to oxic region --> solubles oxidized --> insoluble metal oxides and hydroxides precipitate --> oxidized metals in sediment --> metals reduced by bacterium (as e- acceptors) --> soluble
Carbon dioxide and methane are potent greenhouse gases, with methane having 20 times more warming potential in the atmosphere than CO2. As global warming progresses, there is the real possibility that increased temperatures on land and in the oceans will lead to a positive feedback effect leading to accelerated warming. From the carbon reservoirs listed below with their percentage of the total carbon on Earth, what would be the most dangerous potential source of C that could be released to potentiate further warming?
A fossil fuels (0.006%)
B methane hydrates (0.014%)
C oceans and terrestrial biosphere (0.053%)
D rocks and sediments (99.5%)
Many nutrient cycles are coupled and changes in one cycle will affect another. This means that a change in the amount of carbon dioxide fixed is intimately affected by the amount of __________.
A nitrogen available in an ecosystem
B methane available in an ecosystem
C oxygen available in an ecosystem
D hydrogen available in an ecosystem
As nutrients cycle in the biosphere, __________ can participate in every transformation from one chemical form of a nutrient to another.
Decomposition of organic carbon ultimately results in the formation of __________.
A CO2 in aerobic environments and CH4 in anoxic environments
B CH4 in aerobic environments and CO2 in anoxic environments
C CO2 in aerobic environments and CO2 plus CH4 in anoxic environments
D CO2 plus CH4 in aerobic environments and CH4 in anoxic environments
Which of the following is/are NOT a degradation product of organic material?
B carbon dioxide
D carbon dioxide, methane, and oxygen
Which organisms form the foundation of the carbon cycle?
A anaerobic chemolithotrophs
Frozen methane molecules are called
A methane anhydrates.
B methane hydrates.
C anoxic methane.
D anhydrous methane.
What is a characteristic of a deep sea marine cold seep/vent?
C rich in methane
D low pressure
NO OXYGEN (SO METHOGENESIS FLOURISHES)
What is the largest carbon sink on Earth?
A terrestrial biosphere
B fossil fuels
C rocks and sediments
D aquatic biosphere
The largest reservoir of methane is found
A trapped in volcanic rocks.
B in the rumen of cows and other ruminant animals.
C in the atmosphere.
D trapped under permafrost and marine sediments.
Human activities have disrupted the carbon cycle by
A burning methane hydrates to produce electricity.
B decreasing the primary productivity of the oceans, resulting in increased atmospheric carbon dioxide.
C burning carbon stored as fossil fuels or biomass, thus increasing the amount of carbon dioxide in the atmosphere.
D acidifying the ocean, resulting in the release of large amounts of dissolved carbon dioxide into the atmosphere.
A process where different microbial taxa work in cooperation to degrade a compound that neither can perform entirely on their own is called
The primary energy source for termites comes from
A methanogenic Bacteria.
B methanogenic Archaea.
C acetogenic Archaea.
D acetogenic Bacteria.
Lignin is a complex polymer of methoxylated ________ compounds and is present in ________.
A aromatic / vascular plant material
B oil / fossil fuels
C mineral / rocks
D silica / aquatic environments
In anoxic environments, organic compounds are cycled back to carbon dioxide and methane by __________.
C cellular respiration
Both ammonium (NH4+) and nitrate (NO3-) are assimilated by primary producers, but ammonium is the preferred form of nitrogen for fertilizers used in agriculture because __________.
ammonium is converted to nitrate by microbial nitrification
ammonium does not cause eutrophication (algal blooms) if it enters aquatic ecosystems
nitrate leaches out of soils easily due to its negative charge
ammonium leaches out of soils easily due to its positive charge
Denitrification contributes to global warming by __________.
A destroying ozone
B decreasing the amount of organic nitrogen in the soil
C increasing the amount of carbon dioxide released
D increasing soil pH
The metabolic process of denitrification
A reduces NO3-.
B oxidizes N2.
C oxidizes NO3-.
D reduces N2.
The metabolic process of ammonification ________ ammonia.
Nitrate (NO3-) reduced into ammonia (NH3) to produce energy for the cell is called
C dissimilative reduction of nitrate to ammonia (DRNA).
Which compound in fertilizer do farmers use to inhibit the production of easily leached nitrogen compounds?
A anhydrous ammonia
What is the main form of nitrogen found on Earth?
Which of the following processes does denitrification contribute to?
A acid rain
B global warming
C ozone depletion
D acid rain, ozone depletion, and global warming
Nitrogen fixation results in the
A addition of biologically available N to an ecosystem.
B loss of biologically available N from an ecosystem.
C formation of nitrogen gas.
D direct formation of nitrate.
Nitrous oxide (N2O) is a
A potent greenhouse gas.
B potent greenhouse gas that is a product of denitrification.
C product of denitrification.
D product of nitrification.
Nitrification and anammox both
A oxidize ammonia, but nitrification uses O2 and anammox uses NO2- for electron acceptors.
B occur in soils at neutral pH.
C create nitrogen gas, but nitrification is aerobic while anammox is anaerobic.
D are aerobic processes, but nitrification produces NO3- and annamox produces N2 gas.
Human influences on the carbon cycle may cause major upsets in the balance of the ecosystem because __________.
A increasing the anthropogenic carbon dioxide released in the atmosphere may significantly decrease the amount of calcium carbonate in the deep ocean
B increasing the anthropogenic carbon dioxide released in the atmosphere is significantly increasing the pH of the oceans
C increasing the anthropogenic carbon dioxide released in the atmosphere may significantly increase the amount of ozone in the atmosphere
D increasing the anthropogenic carbon dioxide released in the atmosphere is decreasing the temperature of the oceans
Why would using nitrogenous fertilizer near a body of water affect the organisms in the body of water?
A When runoff enters the body of water, the nitrogen level significantly decreases, which increases the activity of the microorganisms there and upsets the balance of the ecosystem.
B When runoff enters the body of water, the nitrogen level significantly increases, which decreases the activity of the microorganisms there and upsets the balance of the ecosystem.
C It would not affect the organisms in the water, only those in the soil where the fertilizer is applied.
D When runoff enters the body of water, the nitrogen level significantly increases, which increases the activity of the microorganism there and upsets the balance of the ecosystem.
Agricultural application of nitrogen fertilizer
A has little to no effect on the carbon cycle.
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 reduces global warming by increasing the storage of carbon dioxide in plant biomass.
A such as CO2 and O3 (ozone) interact with UV light and heat the Earth.
B such as CO2 increase plant and animal growth, resulting in more heat production on Earth.
C 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.
D such as CO2, CH4, and N2O trap infrared radiation and heat the Earth.
The ocean has mitigated the impact of anthropogenic carbon dioxide production by
A storing 600 billion tons of organic carbon.
B absorbing 500 billion tons of atmospheric carbon dioxide and over 80% of the trapped heat energy.
C absorbing over 80% of the trapped heat energy.
D absorbing 500 billion tons of atmospheric carbon dioxide.
Which statement exemplifies the biological pump concept?
A Calcium ions are brought into cells while toxic physiological byproducts are released.
B Autotrophs bring in light photons to synthesize ATP.
C Primary producers sink to the deep ocean, which provides deep ocean organisms with nutrients when the primary producers die.
D Bacteria oxidize Fe2+ into Fe3+, and Archaea reduce Fe3+ back into Fe2+.
The two major forms of carbon that remain following microbial degradation are
A lignin and fossil fuels.
B methane and carbon dioxide.
C organic matter and hydrocarbons.
D methane, organic matter, and fossil fuels.