Deck 24: Nutrient Cycles, Biodegradation, and Bioremediation

Question 1

What is the function of mercuric reductase?

A) CH3Hg+ to Hg2+
B) Hg2+ to Hg0
C) CH₃HgCH₃ to Hg²⁺ D) Hg⁴⁺ to Hg²⁺

Answer 1

B

Question 2

When microorganisms degrade oil, the carbon is oxidized to

A) methanol.
B) methane.
C) carbon dioxide.
D) carbon monoxide.

Answer 2

C

Question 3

Which organisms form the foundation of the carbon cycle?

A) chemoheterotrophs
B) phototrophs
C) chemoorganotrophs
D) anaerobic chemolithotrophs

Answer 3

B

Question 4

Which is the MOST toxic form of mercury?

A) Hg2+
B) CH3Hg+
C) Hg4+
D) Hg0

Question 5

The primary energy source for termites comes from

A) methanogenic Bacteria.
B) methanogenic Archaea.
C) acetogenic Bacteria.
D) acetogenic Archaea.

Question 6

What is the main form of nitrogen found on Earth?

A) NO3-
B) N2
C) NH4
D) NO

Question 7

One procedure that treats sewage for disposal is the removal of to minimize potential algal blooms associated with sewage discharge into a body of water.

A) cyanophages
B) carbonate
C) sulfate
D) nitrate

Question 8

What substrate does Alcanivorax borkumensis grow on?

A) pyrite
B) humus
C) glyphosate
D) hydrocarbons

Question 9

The temperature of a copper- leaching dump

A) at a given time determines which microorganism is active and which are not.
B) remains at an optimal temperature of 30°C throughout the process.
C) remains at an optimal temperature of 80°C throughout the process.
D) dramatically fluctuates due to endothermic reactions and exothermic reactions that each take place.

Question 10

Nitrate (NO3- ) reduced into ammonia (NH3) is called

A) redox.
B) dissimilative reduction of nitrate to ammonia (DRNA).
C) ammonification.
D) nitrification.

Question 11

The metabolic process of denitrification

A) oxidizes NO3- .
B) reduces NO3- .
C) reduces N2.
D) oxidizes N2.

Question 12

Which of the following is NOT a degradation product of organic material?

A) carbon dioxide
B) oxygen
C) methane
D) all of the above

Question 13

Diatoms require silicon due to their

A) DNA replication mechanism.
B) unique phototrophic physiology.
C) ornate frustules.
D) Ca²⁺/Si⁴⁺ symporters.

Question 14

When dimethylsulfoniopropionate (DMSP) is aerobically degraded in a marine environment, which product is most often used to support growth?

A) acrylate
B) dimethyl sulfoxide
C) methanethiol
D) dimethyl disulfide

Question 15

Frozen methane molecules are called

A) methane anhydrate.
B) anhydrous methane.
C) anoxic methane.
D) methane hydrate.

Question 16

Mercury is NOT used in

A) neurotoxins.
B) pesticides.
C) paper pulping.
D) electronics.

Question 17

The burning of fossil fuels produces significant amounts of

A) sulfur dioxide.
B) sulfite.
C) sulfonate.
D) sulfate.

Question 18

Which statement exemplifies the biological pump concept?

A) Autotrophs bring in light photons to synthesize ATP.
B) Calcium ions are brought into cells while toxic physiological byproducts are released.
C) Bacteria oxidize Fe2+ into Fe3+, and Archaea reduce Fe3+ back into Fe2+.
D) Primary producers sink to the deep ocean, which provides deep ocean organisms with nutrients when the primary producers die.

Question 19

The metabolic process of ammonification _ ammonia.

A) produces
B) reduces
C) oxidizes
D) transforms

Question 20

Which of the following is a sulfide?

A) S2-
B) H2S
C) HS-
D) all of the above

Question 21

The most detected groundwater contaminant are

A) polyaromatic hydrocarbons (PAHs).
B) chlorobenzenes.
C) mercury compounds.
D) polychlorinated biphenyls (PCBs).

Question 22

In the oceans, sulfur exists primarily as , and in rocks and sediments sulfur occurs mostly as and .

Question 23

Lignin is a complex polymer of methoxylated compounds and is present in many
.

Question 24

Which compound in fertilizer do farmers use to inhibit the production of easily leached nitrogen compounds?

A) nitrate
B) anhydrous ammonia
C) carbonate
D) nitrapyrin

Question 25

Coccolithophores and foraminiferans both use to form their exoskeletons.

Question 26

The two major forms of carbon that remain following microbial degradation are _ and .

Question 27

occurs when an organism degrades a compound only when catabolism of a different organic compound ensues.

Question 28

Environments contaminated with chlorinated xenobiotics are generally _ , which highlights the importance of being studied to detoxify these compounds.

Question 29

Calcium carbonate (CaCO3) precipitation results in the of surface dissolved bicarbonate (HCO3- ) and the in dissolved CO2.

Question 30

What is a characteristic of a cold seep/vent?

A) low pressure
B) rich in methane
C) acidic
D) luminous

Question 31

Cells that produce chemicals are well- adapted for catabolizing oil by breaking it up and solubilizing the oil.

Question 32

Which iron species is produced primarily from iron smelting and rarely is produce by microbial- mediated processes?

A) ferric iron (Fe3+)
B) ferrous iron (Fe2+)
C) iron (Fe⁰)
D) ferrulic iron (Fe¹⁺)

Question 33

A process where different microbial taxa work in cooperation to degrade a compound that neither can perform entirely on their own is called

A) syntrophy.
B) allotrophy.
C) commensalism.
D) ammensalism.

Question 34

Why is gold mining often performed in bioreactor tanks?

A) Gold mining requires only a few steps.
B) The bioreactor's temperature must be monitored and regulated due to stringent temperature requirements.
C) Some processing products are highly toxic.
D) all of the above

Question 35

Cyanophages that infect marine cyanobacteria release the major osmoregulatory solute, dimethylsulfoniopropionate (DMSP), which is degraded into the most abundant organic S compound in nature, _.

Question 36

is a term used to describe dead organic matter.

A) Pyrite
B) Loam
C) Humus
D) Xenocompost

Question 37

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

A) syntrophic utilization of sulfite
B) organic carbon production due to anaerobes
C) soil acidification due to chemolithotrophs
D) dimethyl sulfide production due to mixotrophs

Question 38

Which bacterial genera is used in bioremediation of toxic metals?

A) Geobacter
B) Desulfovibrio
C) Shewanella
D) all of the above

Question 39

Bacterial oxidation of Fe2+ occurs BEST under which environmental condition?

A) nutrient replete
B) cold temperature
C) low (acidic) pH
D) high sunlight

Question 40

Using a Roseobacter strain to clean up an oil spill is an example of .

Question 41

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

Question 42

Silicoflagellates use silicon compounds in substrate- level phosphorylation.

Question 43

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

Question 44

Some bacteria have genes that confer resistance to mercury.

Question 45

Nitrite (NO2- ) ions are formed when nitric oxide (NO) and react in the upper atmosphere, which returns to the Earth as in the form of precipitation.

Question 46

Phosphonate comprises 25% of the organic phosphorous pool in waters.

Question 47

In the Earth's atmosphere, methane exists as a _, but it can also occur as a solid under _ and _ conditions.

Question 48

Abiotic oxidation of Fe2+ requires oxygen; no other chemicals can oxidize Fe2+.

Question 49

The most effective bioremediation effort in cleaning up an oil spill quickly requires aerobic microorganisms.

Question 50

In the recovery of copper, Fe2+ is used to oxidize CuS and release Cu2+ leachate.

Question 51

The most dominant aquatic and terrestrial phototrophs are phototrophic microorganisms.

Question 52

Some hydrocarbons volatilize abiotically, without any biological processing.

Question 53

Sulfide is toxic to respiring organisms, because it can combine with ligands present in _ _ that serve a critical function in respiration.

Question 54

The largest carbon sink on Earth is the and of Earth's crust.

Question 55

The copolymer poly- B- hydroxybutryate is an example of a _, because the material came from microorganisms that are capable of degrading the polymer as well.

Question 56

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

Question 57

The animals living near hydrothermal vents tend to eat primarily chemolithotrophic bacteria.

Question 58

In a global sense, all nutrient cycles are coupled together.

Question 59

Most chemolithotrophic bacteria that oxidize sulfur are aerobes.

Question 60

The genus Ferroplasma is commonly associated with iron oxidation in environments that contain high _ and content.

Question 61

Xenobiotics are among the most recalcitrant compounds known on the Earth.

Question 62

Acetogens can ferment glucose into acetate, but methanogens cannot.

Question 63

Changing the oxidation state of a metal is not, by definition, considered bioremediation because the metal itself is still harmful.

Question 64

Syntrophic organisms cannot exist without at least one other organism.

Question 65

Why is sulfur cycling more complex to study than other nutrient cycles such as the nitrogen cycle? How might this influence researchers whose primary research interest is in understanding sulfur cycling?

Question 66

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

Question 67

Microbial processing is necessary to mine uranium.

Question 68

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

Question 69

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

Question 70

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

Question 71

Why is the water solubility of different nitrogen species of importance to agriculturalists?

Question 72

Provide an example of a "new" pollutant, and explain why it is an emerging concern.

Question 73

The precipitation of iron ions into solid forms it is often due to exposure of organic carbon compounds.

Question 74

Describe how microbial leaching is used in the mining of copper. Why is this method preferred over others?

Question 75

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

Question 76

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

Question 77

Describe a reason why microorganisms capable of degrading petroleum do not readily destroy oil tank wells and other petroleum reserves.

Question 78

Describe how syntrophy helps explain why certain enrichments yield consortia and never an individual species.

Question 79

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

Question 80

Denitrification of treated sewage can result in harmful algal blooms.