Bacteria Ecology

Place the steps of root nodule formation in the correct order.1. bacteroids 2. Nod factor secretion 3. invasion 4. recognition of partners 5. mature nodule - 4, 2, 3, 1, 5 - 4, 2, 1, 3, 5 - 4, 1, 2, 3, 5 - 4, 3, 2, 1, 5

- 4, 2, 3, 1, 5

What is a characteristic of a deep sea marine cold seep/vent? - low pressure - luminous - acidic - rich in methane

- rich in methane

What is the largest carbon sink on Earth? - rocks and sediments - fossil fuels - terrestrial biosphere - aquatic biosphere

- rocks and sediments

Plant root nodules are - harmful to plants, because the bacteria outcompete the plants for nutrients. - structures created by fungi and are found in all agricultural crops. - sites where nitrogen fixation occurs. - formed from gall-rotting bacteria that decompose plant roots.

- sites where nitrogen fixation occurs.

Greenhouse gases - such as CO2, CH4, and N2O trap infrared radiation and heat the Earth. - such as CO2 increase plant and animal growth, resulting in more heat production on Earth. - such as CO2 and O3 (ozone) interact with UV light and heat the Earth. - 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.

- such as CO2, CH4, and N2O trap infrared radiation and heat the Earth.

A process where different microbial taxa work in cooperation to degrade a compound that neither can perform entirely on their own is called - commensalism. - allotrophy. - ammensalism. - syntrophy.

- syntrophy.

Lichens are a mutualistic association of a fungus and either an alga or a cyanobacterium in which - the fungus protects the photosynthetic partner from erosion. - the phototroph provides phosphorus to the fungus. - the fungus slowly engulfs the photosynthetic partner. - the fungus helps collect sunlight for the photosynthetic partner.

- the fungus protects the photosynthetic partner from erosion.

The largest reservoir of methane is found - in the rumen of cows and other ruminant animals. - trapped in volcanic rocks. - trapped under permafrost and marine sediments. - in the atmosphere.

- trapped under permafrost and marine sediments.

Decomposition of organic carbon ultimately results in the formation of __________. - CO2 plus CH4 in aerobic environments and CH4 in anoxic environments - CO2 in aerobic environments and CO2 plus CH4 in anoxic environments - CH4 in aerobic environments and CO2 in anoxic environments - CO2 in aerobic environments and CH4 in anoxic environments

- CO2 in aerobic environments and CO2 plus CH4 in anoxic environments

________ is a term used to describe dead organic matter. - Pyrite - Humus - Loam - Xenocompost

- Humus

What is the main form of nitrogen found on Earth? - NH4 - NO - NO3- - N2

- N2

Which statement exemplifies the biological pump concept? - Bacteria oxidize Fe2+ into Fe3+, and Archaea reduce Fe3+ back into Fe2+. - Autotrophs bring in light photons to synthesize ATP. - Primary producers sink to the deep ocean, which provides deep ocean organisms with nutrients when the primary producers die. - Calcium ions are brought into cells while toxic physiological byproducts are released.

- Primary producers sink to the deep ocean, which provides deep ocean organisms with nutrients when the primary producers die.

What benefit does the fungal partner get from the lichen relationship? - The alga provides organic compounds for food to the fungus. - The alga facilitates water uptake. - The alga anchors the fungus to the substrate. - The alga produces lichen acids that help provide inorganic nutrients from the substrate.

- The alga provides organic compounds for food to the fungus.

Why would using nitrogenous fertilizer near a body of water affect the organisms in the body of water? - 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. - It would not affect the organisms in the water, only those in the soil where the fertilizer is applied. - 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. - 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.

- 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.

The ocean has mitigated the impact of anthropogenic carbon dioxide production by - absorbing over 80% of the trapped heat energy. - absorbing 500 billion tons of atmospheric carbon dioxide. - storing 600 billion tons of organic carbon. - absorbing 500 billion tons of atmospheric carbon dioxide and over 80% of the trapped heat energy.

- absorbing 500 billion tons of atmospheric carbon dioxide and over 80% of the trapped heat energy.

The primary energy source for termites comes from - methanogenic Archaea. - acetogenic Archaea. - methanogenic Bacteria. - acetogenic Bacteria.

- acetogenic Bacteria.

Which of the following processes does denitrification contribute to? - acid rain - global warming - ozone depletion - acid rain, ozone depletion, and global warming

- acid rain, ozone depletion, and global warming

Increasing atmospheric carbon dioxide is - increasing sedimentation of C, Ca, and Si. - fueling increased primary production in ocean waters. - increasing the effect of the biological pump. - acidifying the ocean and decreasing the rate of formation of calcareous shells.

- acidifying the ocean and decreasing the rate of formation of calcareous shells.

Nitrogen fixation results in the - formation of nitrogen gas. - direct formation of nitrate. - addition of biologically available N to an ecosystem. - loss of biologically available N from an ecosystem.

- addition of biologically available N to an ecosystem.

Lignin is a complex polymer of methoxylated ________ compounds and is present in ________. - mineral / rocks - silica / aquatic environments - aromatic / vascular plant material - oil / fossil fuels

- aromatic / vascular plant material

Two main symbionts of termites are ________ and ________. - fungi / protists - bacteria / fungi - archaea / bacteria - bacteria / protists

- bacteria / protists

The function of leghemoglobin in root nodules is to - chelate iron. - produce iron. - bind oxygen. - produce nitrogen.

- bind oxygen.

Human activities have disrupted the carbon cycle by - acidifying the ocean, resulting in the release of large amounts of dissolved carbon dioxide into the atmosphere. - decreasing the primary productivity of the oceans, resulting in increased atmospheric carbon dioxide. - burning carbon stored as fossil fuels or biomass, thus increasing the amount of carbon dioxide in the atmosphere. - burning methane hydrates to produce electricity.

- burning carbon stored as fossil fuels or biomass, thus increasing the amount of carbon dioxide in the atmosphere.

How is a bacteroid distinguished from a bacterial cell? - biochemical tests - 16S rRNA gene sequencing, biochemical tests, and cell morphology - 16S rRNA gene sequencing - cell morphology

- cell morphology

Denitrification contributes to global warming by __________. - increasing soil pH - destroying ozone - increasing the amount of carbon dioxide released - decreasing the amount of organic nitrogen in the soil

- destroying ozone

Nitrate (NO3-) reduced into ammonia (NH3) to produce energy for the cell is called - dissimilative reduction of nitrate to ammonia (DRNA). - redox. - ammonification. - nitrification.

- dissimilative reduction of nitrate to ammonia (DRNA).

In anoxic environments, organic compounds are cycled back to carbon dioxide and methane by __________. - metabolism - cellular respiration - glycolysis - fermentation

- fermentation

Benefits of a nodulated plant include __________. - decreased oxygen produced through photosynthesis - decreased nitrogen available to the plant - increased oxygen produced through photosynthesis - increased plant yield

- increased plant yield

The specificity of certain rhizobia to infect only particular plants is in part due to the - rhizobial lipids that act as signaling molecules. - abundance of nutrients present in the soil. - season (time of year). - nifH genes they possess.

- rhizobial lipids that act as signaling molecules.

Human influences on the carbon cycle may cause major upsets in the balance of the ecosystem because __________. - increasing the anthropogenic carbon dioxide released in the atmosphere is significantly increasing the pH of the oceans - increasing the anthropogenic carbon dioxide released in the atmosphere may significantly decrease the amount of calcium carbonate in the deep ocean - increasing the anthropogenic carbon dioxide released in the atmosphere may significantly increase the amount of ozone in the atmosphere - increasing the anthropogenic carbon dioxide released in the atmosphere is decreasing the temperature of the oceans

- increasing the anthropogenic carbon dioxide released in the atmosphere may significantly decrease the amount of calcium carbonate in the deep ocean

A farmer finds that his soybean plants do not look healthy. They appear stunted and the leaves are a yellowish color, indicating possible lack of nitrogen. To have a more successful crop next year, he should consider__________. - fertilizing with ammonia fertilizer - fertilizing his fields with iron. - inoculating his fields with the appropriate cross-inoculation group of rhizobia - increasing irrigation of his fields.

- inoculating his fields with the appropriate cross-inoculation group of rhizobia

The role of the iron-containing leghemoglobin in the rhizobial root nodules of soybeans is to __________. - lower the amount of free O2 in the root nodule - carry iron to the rhizobial bacteria - carry O2 from the root nodule to the leaves - carry O2 from the leaves to the root nodule

- lower the amount of free O2 in the root nodule

The two major forms of carbon that remain following microbial degradation are - methane, organic matter, and fossil fuels. - lignin and fossil fuels. - organic matter and hydrocarbons. - methane and carbon dioxide

- methane and carbon dioxide

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? - fossil fuels (0.006%) - rocks and sediments (99.5%) - oceans and terrestrial biosphere (0.053%) - methane hydrates (0.014%)

- methane hydrates (0.014%)

Frozen methane molecules are called - anoxic methane. - anhydrous methane. - methane anhydrates. - methane hydrates.

- methane hydrates.

Two organisms that both benefit from each other are in a symbiotic relationship called - mutualism. - commensalism. - parasitism. - ammensalism.

- mutualism.

Which compound in fertilizer do farmers use to inhibit the production of easily leached nitrogen compounds? - anhydrous ammonia - nitrapyrin - nitrate - carbonate

- nitrapyrin

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 leaches out of soils easily due to its positive charge - ammonium does not cause eutrophication (algal blooms) if it enters aquatic ecosystems - nitrate leaches out of soils easily due to its negative charge - ammonium is converted to nitrate by microbial nitrification

- nitrate leaches out of soils easily due to its negative charge

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 __________. - hydrogen available in an ecosystem - oxygen available in an ecosystem - nitrogen available in an ecosystem - methane available in an ecosystem

- nitrogen available in an ecosystem

Some lichen symbionts can survive independently on bare rocks in the absence of any external source of organic matter due to the ability of the phototrophic partner to fix CO2 from the air, and __________. - chemolithotrophy by the bacterial partner. - acquisition of water by the algal partner - production of acids by bacterial fermenters to release minerals from the rock. - nitrogen fixation by the cyanobacterial partner

- nitrogen fixation by the cyanobacterial partner

Bacterial symbionts of termite hindguts play a critical role in the termite's - nitrogen metabolism. - reproduction and nitrogen metabolism. - reproduction. - resistance to fungal infection.

- nitrogen metabolism.

Nitrification and anammox both - create nitrogen gas, but nitrification is aerobic while anammox is anaerobic. - are aerobic processes, but nitrification produces NO3- and annamox produces N2 gas. - occur in soils at neutral pH. - oxidize ammonia, but nitrification uses O2 and anammox uses NO2- for electron acceptors.

- oxidize ammonia, but nitrification uses O2 and anammox uses NO2- for electron acceptors.

Which of the following is/are NOT a degradation product of organic material? - carbon dioxide, methane, and oxygen - oxygen - methane - carbon dioxide

- oxygen

Which organisms form the foundation of the carbon cycle? - chemoorganotrophs - phototrophs - anaerobic chemolithotrophs - chemoheterotrophs

- phototrophs

Nitrous oxide (N2O) is a - product of denitrification. - potent greenhouse gas that is a product of denitrification. - product of nitrification. - potent greenhouse gas.

- potent greenhouse gas that is a product of denitrification.

The metabolic process of ammonification ________ ammonia. - reduces - transforms - produces - oxidizes

- produces

As nutrients cycle in the biosphere, __________ can participate in every transformation from one chemical form of a nutrient to another. - prokaryotes - animals - plants - fungi

- prokaryotes

The metabolic process of denitrification - oxidizes N2. - reduces NO3- - reduces N2. - oxidizes NO3-.

- reduces NO3-

Most nitrogen-fixing bacteria symbiotically associated with plants are called - bacteroids. - symbiodinia. - mycorrhizae. - rhizobia.

- rhizobia.

The mutualism of Azolla-Anabaena is useful for - tropical forest community succession. - rice farmers. - aquaculturalists. - corn farmers.

- rice farmers.

Agricultural application of nitrogen fertilizer = has little to no effect on the carbon cycle. = reduces global warming by increasing the storage of carbon dioxide in plant biomass. = increases global warming by increasing microbial respiration in agricultural soils. = increases global warming by increasing the production of nitrous oxide (N2O) by denitrification in agricultural soils.

= increases global warming by increasing the production of nitrous oxide (N2O) by denitrification in agricultural soils.