(Final) Microbiology Chapter 21- Nutrient Cycles in Nature

The ocean has mitigated the impact of anthropogenic carbon dioxide production by

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

The primary energy source for termites comes from

Acetogenic Bacteria.

Which of the following processes does denitrification contribute to?

Acid rain, ozone depletion, and global warming

Increasing atmospheric carbon dioxide is

Acidifying the ocean and decreasing the rate of formation of calcareous shells.

When dimethylsulfoniopropionate (DMSP) is aerobically degraded...

Acrylate

Nitrogen fixation results in the

Addition of biologically available N to an ecosystem.

Lignin is a complex polymer of methoxylated...

Aromatic / vascular plant material

Lysis of marine algae and cyanobacteria releases the major osmoregulatory...

Dimethyl sulfide (CH3-S-CH3)

Nitrate (NO3-) reduced into ammonia (NH3)...

Dissimilative reduction of nitrate to ammonia (DRNA).

(TF)Calcium is cycled most rapidly in terrestrial environments.

False

(TF)Carbon dioxide is the only greenhouse gas produced by anthropogenic activities.

False

(TF)Climate scientists are developing methane hydrates to decrease the effects of global warming.

False

(TF)Denitrification of fertilizer can result in harmful algal blooms.

False

(TF)Energy yields are high enough for Fe2+ oxidation that the bacteria that perform this reaction require only small quantities of Fe2+ to be available.

False

(TF)Humic acids are difficult to degrade, and therefore they usually remain in a system for several decades.

False

(TF)Methanogens, among other compounds, use alcohols and fatty acids to synthesize methane gas in anoxic environments.

False

(TF)Microbial activity generates methylmercury, which is much less toxic than the mercuric ion.

False

(TF)Silicoflagellates use silicon compounds in substrate-level phosphorylation.

False

(TF)The mercury in fish is normally in the form of elemental mercury (Hg0).

False

(TF)The precipitation of soluble iron ions into solid iron occurs spontaneously in the presence of organic carbon compounds.

False

(TF)When carbon is limiting in a system, sulfate reducers often predominate the system when sufficient sulfate ions are present for reduction.

False

The oxidation of _ occurs both biotically and abiotically...

Fe2+ / low

Which of the following is a sulfide?

H2S, HS-, and S2- are all sulfides.

What reaction is catalyzed by mercuric reductase?

Hg2+ to Hg0

_ is a term used to describe dead organic matter.

Humus

Sulfide is toxic to respiring organisms...

Cytochromes

The Fe and Mn cycles include

Reduced and oxidized forms that are very chemically reactive.

The metabolic process of denitrification

Reduces NO3-.

What is a characteristic of a deep sea marine...

Rich in methane

What is the largest carbon sink on Earth?

Rocks and sediments

What would the result be when a soil is supplemented with S0?

Soil acidification due to chemolithotrophs

Greenhouse gases

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

In the oceans, sulfur exists primarily as...

Sulfate (SO42-) / gypsum (CaSO4) / pyrite (FeS2)

The burning of fossil fuels produces significant amounts of

Sulfur dioxide.

A process where different microbial taxa work...

Syntrophy.

One important difference between the C, N, and S...

The P, Ca, and Si cycles do NOT involve redox changes or gaseous forms that can alter Earth's atmospheric chemistry.

Human activities have disrupted the carbon cycle by

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

Which is the MOST toxic form of mercury?

CH3Hg+

Coccolithophores and foraminiferans both use...

Ca2+

The Ca cycle is tightly coupled to the

Carbon cycle through calcium carbonate formation in ocean waters.

Agricultural application of nitrogen fertilizer

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

Which iron species is produced primarily from iron smelting...

Iron (Fe0)

Bacterial oxidation of Fe2+ occurs BEST...

Low (acidic) pH

The two major forms of carbon...

Methane and carbon dioxide.

Frozen methane molecules are called

Methane hydrates.

What is the main form of nitrogen found on Earth?

N2

Which compound in fertilizer do farmers...

Nitrapyrin

Studying the redox cycling of Fe...

Of bacteria that transfer electrons long distances and generate electric currents.

Phosphonate comprises 25% of the...

Organic

Nitrification and anammox both

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

Which of the following is/are NOT a degradation...

Oxygen

Mercury is NOT used in

Paper pulping.

Which organisms form the foundation of the carbon cycle?

Phototrophs

Nitrous oxide (N2O) is a

Potent greenhouse gas that is a product of denitrification.

Which statement exemplifies the biological pump concept?

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

The metabolic process of ammonification _ ammonia.

Produces

The largest reservoir of methane is found

Trapped under permafrost and marine sediments.

(TF)Abiotic oxidation of Fe2+ requires oxygen; no other chemicals can directly oxidize Fe2+.

True

(TF)Acetogens can ferment glucose into acetate, but methanogens cannot.

True

(TF)In a global sense, ALL nutrient cycles are coupled together.

True

(TF)In the natural carbon cycle, carbon dioxide is returned to the atmosphere by the respiration of animals and chemoorganotrophic microorganisms.

True

(TF)Mercury can serve as a transcriptional activator in the regulation of certain genes.

True

(TF)Mercury has both organic and inorganic forms that are neurotoxic.

True

(TF)Mercury-resistant bacteria detoxify mercury by producing Hg0.

True

(TF)More carbon is present in dead organic material on Earth than in living organisms.

True

(TF)Most chemolithotrophic bacteria that oxidize sulfur are aerobes.

True

(TF)Most phosphorous, such as that found in inorganic phosphate (HPO4-), exist in the +5 oxidation state in nature.

True

(TF)Ocean acidification decreases the precipitation of calcium carbonate and thus will probably affect the cycling of Ca and other nutrients in the ocean.

True

(TF)Some bacteria have genes that confer resistance to mercury.

True

(TF)Syntrophic organisms cannot grow fermentatively without a hydrogen-consuming partner organism.

True

(TF)The disposal of garbage or sewage in the ocean is known to cause the sudden growth of sulfate reducers.

True

(TF)The two main biological activities in the Ca and Si cycles are the biosynthesis of shells and exoskeletal material as well as the mineralization of these materials in sediments.

True