Deck 22: Microbes and the Global Environment

Question 1

Marine dead zones are characterized as being:

A) hypoxic
B) aerated
C) devoid of fish
D) A and C
E) dangerous for ship sail

Answer 1

D

Question 2

Which of the following is NOT an example of a reduced form of carbon in the carbon cycle?

A) methane
B) biomass
C) hydrocarbons
D) carbon dioxide
E) methanol

Answer 2

D

Question 3

In the marine photic zone, the rate of photosynthesis:

A) is equal to the amount of CO₂ released from the niche
B) exceeds the rate of respiration
C) is less than the respiration rate
D) does not affect carbon cycling
E) is inversely related to rate of respiration

Answer 3

B

Question 4

The relative composition of elements across all species is _____________.

A) constant
B) varied
C) not measurable
D) independent of abiotic factors
E) called its "reservoir"

Question 5

Deforestation contributes to greenhouse effects on Earth primarily through:

A) burning of logs
B) microbial decomposition
C) reduction of terrestrial photosynthesis
D) anaerobic decay of debris
E) loss of plant diversity

Question 6

Which of the following reservoirs contains the most rapidly cycled carbon?

A) atmosphere
B) ocean biomass
C) ocean inorganic molecules
D) land biomass
E) crust below land and ocean

Question 7

The release of CO₂ by human industry has/is __________ the rate of CO₂ fixation globally.

A) equal to
B) tripled
C) outpaced
D) far less than
E) none of the above

Question 8

Microbial activities in rice paddies increase the release of methane. What will happen if the rice paddies are drained and aerated?

A) More methane will be released.
B) Increased carbon dioxide production.
C) No change in the amount of methane generated.
D) All the methanogens will die.
E) Rice roots will absorb the methane.

Question 9

The NASA FLUXNET tower is used for sampling and monitoring which of the following?

A) atmospheric CO₂ and carbon flux
B) dinitrogen gas and denitrification
C) biomass carbon and dissolved CO₂ oceans
D) hydrogen cycle and carbon flux
E) atmospheric nitrogen and carbon

Question 10

Which of the following is CORRECT about micronutrients?

A) They are needed in small amounts and do not need to be cycled.
B) They are sometimes needed in large amounts.
C) Phosphorus is a good example of a micronutrient.
D) Some microbes can grow without them.
E) Their cycling involves changes in oxidation state.

Question 11

Concerning biogeochemical cycles, all of the following are true EXCEPT:

A) Nearly half of nitrogen in the biosphere comes from anthropogenic sources.
B) Carbon dioxide production by human industry has outpaced fixation.
C) Most microbes can interconvert the six major elements, from one to another.
D) Organisms acquire elements from abiotic sources or from other organisms.
E) Metabolic interactions of microbes with biotic and abiotic environ is biogeochemistry.

Question 12

Microbes participate in which step of wastewater treatment?

A) preliminary
B) primary
C) secondary
D) tertiary
E) all of the above

Question 13

Oil spills introduce huge amounts of carbon in the environment. Which of the following techniques is used to quantify carbon influx and efflux of CO₂?

A) gas chromatography
B) mass spectroscopy
C) radioisotope incorporation
D) stable isotope ratios
E) none of the above

Question 14

Much of the carbon and nitrogen in wetlands is cycled by:

A) aerobic respiration
B) plants and aerobic heterotrophs
C) wild fire
D) anaerobic bacteria and archaea such as methanogens
E) cyanobacteria and phototrophs

Question 15

The sink of an element in the ecosystem:

A) is the reservoir to which it returns during cycling
B) is the most accessible reservoir of that element
C) renders the element inaccessible
D) releases the element into the subsurface
E) is the source of the element for living organisms

Question 16

The element with the highest percentage of dry weight in bacteria is:

A) calcium
B) carbon
C) hydrogen
D) nitrogen
E) phosphorus

Question 17

Which of the following is an anaerobic respiration reaction?

A) conversion of phosphine to phosphate
B) methanogenesis
C) photolysis of hydrogen sulfide to sulfur
D) precipitation of ferric iron with hydroxide
E) nitrogen fixation

Question 18

Which of the following is a micronutrient?

A) carbon
B) hydrogen
C) zinc
D) phosphorus
E) nitrogen

Question 19

Ammonium nitrate addition to wetland soil cores is associated with increased CO₂ efflux, presumably caused by the increased respiration by:

A) phototrophs
B) autotrophs
C) heterotrophs
D) lithotrophs
E) methanogens

Question 20

The largest reservoir for carbon is the:

A) atmosphere
B) ocean biomass
C) carbonate rocks and subsurface carbon
D) wetlands
E) fossil fuels

Question 21

The wetlands of the Florida Everglades are more efficient in the removal of organic pollutants than treatment plants because:

A) microbial conversions fix the pollutants into valuable biomass
B) the alligators consume most of the predators/consumers
C) the soil is porous and filters wastes rapidly
D) of microbial conversions and the physical filtration by soil
E) the vast Everglades physically dilutes the pollutants

Question 22

How much of fixed nitrogen comes from the Haber process of chemical fertilizer production?

A) more than 80%
B) at least 30%
C) amount is unknown
D) 65%
E) nearly 20%

Question 23

Which of the following organisms does NOT play a role in secondary wastewater treatment?

A) Zoogloea
B) Flavobacterium
C) Escherichia
D) Pseudomonas
E) Nostoc

Question 24

Which of the following would be more problematic in Kansas than Florida?

A) mercury-contaminated fish
B) nitrite-induced blue baby syndrome
C) uranium-contaminated soil
D) iron-corroded pipes
E) sulfur-contaminated coal

Question 25

Which of the following is the most perturbed of the major biogeochemical cycles?

A) sulfur cycle
B) carbon cycle
C) nitrogen cycle
D) phosphorus cycle
E) hydrogen cycle

Question 26

The conversion of nitrate to dinitrogen gas is called:

A) nitrogen fixation
B) nitrification
C) nitrate assimilation
D) ammonification
E) denitrification

Question 27

Anammox is defined as:

A) anaerobic oxidation of ammonia to nitrogen gas using nitrites
B) cell-wall-less bacteria called Planctomycetes carry out this reaction
C) a rather rare pathway for returning nitrogen to the atmosphere
D) a predominantly terrestrial pathway for cycling nitrogen
E) A and B

Question 28

What types of bacteria will carry out nitrification (conversion of ammonia to nitrite or nitrate)?

A) lithotrophs
B) heterotrophs
C) chemoorganotrophy
D) phototrophs
E) fastidious heterotrophs

Question 29

During wastewater treatment, the secondary treatment requires continual aeration to:

A) augment the bacterial density
B) select for planktonic heterotrophs
C) stimulate chemical degradation
D) increase microaerophilic filamentous bacteria
E) maximize breakdown of molecules to CO₂ and nitrates

Question 30

What do wastewater treatment plants have in common with wetland filtration (purification)?

A) the type of wastewater treated
B) the engineering designs and flow
C) depend on microbes to remove nitrogen and carbon
D) oxygen is used to decontaminate pollutants
E) membrane filtration eliminates the contaminants

Question 31

In polluted ocean waters, what type of organisms may contribute significantly to global warming?

A) photosynthetic bacteria
B) photosynthetic archaea
C) vent bacteria
D) protists
E) denitrifying bacteria

Question 32

Which of the following major elements has the highest number of oxidation states?

A) nitrogen
B) carbon
C) hydrogen
D) sulfur
E) oxygen

Question 33

To enhance colonization by nitrogen fixers, farmers apply attractants for rhizobia called:

A) nitrogenases
B) leghemoglobins
C) hormones
D) isoflavonoids
E) heterocysts

Question 34

Dinitrogen gas constitutes __________ of the atmosphere.

A) 10%
B) 79%
C) 69%
D) 21%
E) 0.03%

Question 35

The highly potent greenhouse gas N₂O generates how many times the warming effect of CO₂?

A) 50
B) 100
C) 150
D) 200
E) 500

Question 36

Denitrification involves the conversion of nitrate to nitrous oxides and nitrogen. Under which of the following conditions or niches do bacteria carry out dissimilatory reduction of nitrate to ammonia?

A) sewage sludge
B) digestive tract of ruminants
C) stagnant polluted water body
D) only two of the above
E) all of the above

Question 37

Which is the most stable form of nitrogen?

A) NO
B) NO
C) N₂
D) NH₃
E) NH

Question 38

Which contaminant in water is especially prevalent in agricultural regions of the United States?

A) carbon
B) sulfur
C) phosphate
D) nitrate
E) magnesium

Question 39

Wastewater treatment generates which of the following gases in quantities sufficient for recovery as fuel?

A) carbon dioxide
B) hydrogen
C) nitrous oxide
D) methane
E) hydrogen sulfide

Question 40

Biological nitrogen fixation (BNF) is inhibited by oxygen. Which of the following statements is NOT correct?

A) Nitrogen fixation is ubiquitous in soil and water.
B) Cyanobacteria are among the significant prokaryotic nitrogen fixers.
C) BNF was the major source of fixed N before the Industrial Revolution.
D) Only anaerobes fix dinitrogen on land.
E) A wide diversity of prokaryotes use same enzyme-nitrogenase for nitrogen fixation.

Question 41

Which of the following is a major concern regarding biogeochemical and industrial sources of atmospheric sulfur?

A) greenhouse effect
B) acid rain
C) ozone depletion
D) inhibition of photosynthesis
E) all of the above

Question 42

What is the role of predators in wastewater treatment plants?

Question 43

Which of the following can assimilate Fe³⁺?

A) archaea
B) bacteria
C) haloarchaea
D) fungi
E) all of the above

Question 44

Discuss the ecological benefits of wetlands.

Question 45

On which of the following planets does humankind expect to find life because of the similarity of its geology with that of Earth?

A) Jupiter
B) Venus
C) Mars
D) Jupiter's moon Europa
E) Pluto

Question 46

In 2010, the dead zone in the Gulf of Mexico expanded because of the unprecedented oil spill caused by the Deepwater Horizon oil well explosion. The leaked oil killed wildlife and caused unprecedented environmental damage. Bacteria came to the rescue. Discuss.

Question 47

What would happen if household wastewater was emptied into local receiving rivers without prior treatment?

Question 48

Which of the following spontaneously ignites with a green glow as it emanates from the ground?

A) pyrite
B) nitrous oxide
C) dimethyl sulfide
D) phosphine
E) dimethylmercury

Question 49

Human burning of petroleum in effect releases CO₂ from the product of ancient bacteria. Discuss.

Question 50

Which of the following is least likely to raise the biochemical oxygen demand?

A) nitrate
B) phosphate
C) sulfate
D) iron
E) organic fertilizer

Question 51

Which of the following is assimilated almost entirely in the oxidized state?

A) sulfur
B) nitrogen
C) phosphate
D) carbon
E) none of the above

Question 52

Describe the wetland system set up by a hog farmer to treat his hog-farm waste.

Question 53

Which of the following is used by bacteria for iron uptake?

A) ferrodoxin
B) protein A
C) hemoglobin
D) siderophores
E) lipoprotein

Question 54

Deforestation contributes to global warming. Discuss deforestation in terms of carbon efflux and influx.

Question 55

Anaerobically, H₂S may be photolyzed to:

A) sulfate
B) sulfite
C) sulfur dioxide
D) sulfuric acid
E) sulfur

Question 56

What is biochemical oxygen demand (BOD)? Why is high BOD undesirable?

Question 57

Explain how isotope ratios can be used to indicate the type of organism present in an ecosystem.

Question 58

Marine water is extremely limited in the supply of phosphate. Which of the following represents a classic microbial adaptation to phosphorous deficiency in this environ?

A) substitution of phospholipids by nonphospholipids on the membrane
B) rapid metabolism to scavenge decomposing plankton
C) elimination of phosphate groups from DNA backbone
D) specialized structures for adsorbing phosphate
E) none of the above

Question 59

Which of the following is the most limiting element in marine ecosystems?

A) iron
B) sulfur
C) carbon
D) phosphorous
E) hydrogen

Question 60

Could human-induced global warming cause mass extinctions of a majority of Earth's species as did the rise of ancient cyanobacteria?

Question 61

Discuss how human activities have perturbed the nitrogen cycle.

Question 62

What types of evidence suggest the past existence of water on Mars?

Question 63

Desulfovibrio desulfuricans plays a role in the corrosion of sewer pipes but is also used in a beneficial way for uranium decontamination. Describe its role in the latter.

Question 64

Explain how the Mississippi River drainage into the Gulf of Mexico off the coast of Louisiana leads to a large dead zone.

Question 65

Nitrogen is a major element for life on Earth. Discuss some of the reasons for its versatile use.

Question 66

Astrobiology is the study of life in the universe. Why might our rDNA probes NOT be appropriate to detect extraterrestrial life?

Question 67

How do certain marine organisms adapt to the paucity of phosphorous supply?

Question 68

What evidence suggests that the biochemistry of life elsewhere would resemble that on Earth?

Question 69

Describe how bacteria have been used to remove uranium contamination.

Question 70

Discuss the concept of iron fertilization to remove excess CO₂ from the atmosphere. Who is the rock star supporting this research?