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Microbio 2302 > Ch.27 Environmental Micro > Flashcards

Ch.27 Environmental Micro Flashcards

1
Q

what is the hydrologic (water) cycle?

A

is the cyclic exchange of water between the atmosphere and biosphere

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2
Q

what are the steps to the hydrologic water cycle?

A
  1. water precipitates as rain; falls to earth
  2. It is returned by evaporation to the air
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3
Q

what carries nutrients into the river and what does it increase?

A
  1. water
  2. increases BOD
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4
Q

what accelerates microbial respiration?

A

Carbon runoff

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5
Q

what is BOD?
Biochemical oxygen Demand

A

it is the amount of O2 removed from the environment through respiration

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6
Q

what creates BOD?

A

Microbial Oxygen Consumption

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7
Q

how is BOD measured?

A

with how fast oxygen is removed

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8
Q

where are dead zones or zones of hypoxia?

A

large regions of the ocean

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9
Q

what is an example of a dead zone or zone of hypoxia?

A

Gulf of Mexico, off the Louisiana coast

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10
Q

when did the dead zone expand?

A

by 2010 oil spill

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11
Q

Heterotrophs in a large region of the ocean that have become dead zones or zones of hypoxia increase in response to what?

A

the influx of organic nutrients

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12
Q

what depletes oxygen in large regions of the ocean that have become dead zones or zones of hypoxia?

A

aerobic respiration

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13
Q

when does eutrophication occur?

A

from an influx of excess nutrients that triggers hypoxic zones in the water

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14
Q

Eutrophication results in high levels of what?

A

aerobic respiration

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15
Q

what decreases the BOD and the level of human pathogens before water is returned to local rivers?

A

wastewater treatment

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16
Q

what are the steps to wastewater treatment?

A
  1. Preliminary treatment
  2. Primary treatment
  3. Secondary Treatment
  4. Tertiary (advanced) treatment
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17
Q

what does the preliminary treatment do?

A

removes solid debris

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18
Q

what does the primary treatment do?

A

fine screens & sedimentation tanks remove insoluble particles.

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19
Q

what does secondary treatment do?

A

microbial decomposition of organic content

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20
Q

what does tertiary advance treatment do?

A

chlorination or other chemical application to eliminate pathogens

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21
Q

what is the activated sludge process?

A

a process for treating wastewater using air and a biological floc composed of bacteria and protozoa.

22
Q

why is flocculation important?

A

floc formation is critical in promoting the setting of bacteria

associated microbes from the treatment process.

23
Q

what does flocculation yield?

A

abundant, clarified effluent

24
Q

what is important in floc formation?

A

filamentous bacteria

25
Q

what is a healthy sludge(brown floc) largely composed of?

A

Saprotrophic bacteria

26
Q

what does saprotrophic bacteria feed on?

A

feed on decayed matter

27
Q

what is the protozoan flora composed of?

A

amoebae
ciliated protozoans
stalked ciliates

28
Q

true or false?
Nitrogen has more oxidation states than any other major biological element

A

true

29
Q

What can’t the nitrogen cycle exist without?

A

it cannot exist without prokaryotes

30
Q

what is the major accessible nitrogen source?

A

atmosphere

31
Q

what is artificial nitrogen fixation accomplished by?

A

by the Haber process

32
Q

what is the Haber process?

A

it generates fertilizers for agriculture
N2+3H2—-> 2NH3

33
Q

What is ammonification?

A

the catabolism of organic N sources (proteins); release ammonia (NH3)

34
Q

The N2 is catalyzed by what?

A

nitrogenase

35
Q

does N2 fixation function anaerobically or aerobically?

A

anaerobically

36
Q

what does symbiotic mean?

A

bacterial associations with certain types of plants

37
Q

what does N2 fixation occur in?

A

free-living types and symbiotic types of bacterial

38
Q

cyanobacteria in oceans and freshwater compartmentalize N2 fixation in what?

A

heterocysts

39
Q

what is the formula for N2 fixation?

A

N2—–>NH3—-NH4+

40
Q

steps to symbiotic N2 fixation:

A
  1. Rhizobia attaches to root hair
  2. An infection thread is formed through which bacteria enter root cells
  3. Bacteria change into bacteroids; packed roots enlarge
  4. Enlarged root cells form a nodule
41
Q

What is the formula for nitrification?

A

NH4+—>NO2- —->NO3-

42
Q

what is lithotrophy?

A

oxidation of NH4+ provides electrons and energy.

43
Q

what does denitrification represent?

A

represents anaerobic respiration

44
Q

what does denitrification lead to?

A

loss of nitrogen from the environment

45
Q

what stimulates denitrification?

A

influx of nitrate(NO3-) into areas lacking O2

46
Q

what happens in hypoxic areas during denitrification?

A

anaerobic respiration using NO3-

causes: NO2- buildup

then used to for N2O

47
Q

what happens when water passes through the ground and picks up nutrients?

A

carbon runoff accelerates microbial respiration

02 becomes depleted

48
Q

High BOD can threaten what?

A

viability of fish & other aquatic animals

49
Q

when does high BOD threaten the viability of aquatic animals?

A

when O2 levels are < 5 mg L

50
Q

what is the process of Eutrophication?

A
  1. influx of N, P boosts levels of phototrophs

ex: alage & cyanobacteria; a mat of growth occurs

  1. once excess N, P is used up, the algal mass dies and falls to the bottom
  2. Hetertropic bacteria on the organic matter feast on organic matter
  3. Aerobic respiration depletes oxygen from the water- fish killed

Microbio 2302 (15 decks)

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