Chapter 21 Flashcards

(38 cards)

1
Q

Which CO2 is the most rapidly fixed

A

Atmosphere

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2
Q

Ways that CO2 is returned to the atmosphere

A

respiration, microbial decomposition (biggest return)

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3
Q

Photosynthesis Reaction

A

-CO2 +H2O –> (CH2O) + O2

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4
Q

Respiration Reaction

A

-(CH2O) + O2 –> CO2 + H2O

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5
Q

Two major end products of decompositio

A

-CH4 & CO2

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6
Q

How is methane effective in cold seeps/deep-sea ecosystems?

A

CH4 under high pressure low temperature becomes trapped
-nourishes anaerobic Arch. and Bac.
(CH4 endosymbionts)

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7
Q

Which two cycles are closely coupled?

A

-Carbon and NItrogen Cycle

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8
Q

KNOW CARBON CYCLE

A

KNOW CARBON CYCLE

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9
Q

KNOW THE COUPLED CYCLE

A

KNOW THE COUPLED CYCLE

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10
Q

What is methanogenesis?

A

central to C cycling in in anoxic environments

i) Reduce CO2 to CH4 with H2 as e- donor
ii) Some can reduce other substrates to CH4

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11
Q

How do methanogensis symbionts benefit the host?

A

by consuming H2 (generated from glucose fermentation)

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12
Q

What is another H2 consuming process besides methanogensis?

A

Acetogenesis (less favorable)

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13
Q

List the Major Nitrogen transformations

A
  1. nitrification
  2. denitrification
  3. anammox
  4. nitrogen fixation
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14
Q

how is nitrogen made

A

reduction of NO3- to NH3

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15
Q

what is responsible for 85% N loss

A

denitrification

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16
Q

KNOW THE NITROGEN CYCLE

A

KNOW THE NITROGEN CYCLE

17
Q

What is nitrogen fixation?

A

the ability to use N2 (few prokaryotes have this ability)

18
Q

What is denitrification?

A

i) Reduction of NO3 to gaseous N products

ii) Primary way N2 is produced biologically

19
Q

Two ways NH3 can be made from N

A
  1. N-fixation

2. ammonification

20
Q

what changes NH3 to N2 gas

A

Anammox-anoxic oxidation

21
Q

KNOW NITRATE REDUCTION FLOW CHART

A

KNOW NITRATE REDUCTION FLOW CHART

22
Q

Focus a lot of nitrate reduction and its various stuff

A

Focus a lot of nitrate reduction and its various stuff

23
Q

Which cycle has to most significant oxidation states

A

Sulfur (-2, 0, 6)

24
Q

Major sulfur reservoirs

A
  1. sediments and rocks

2. ocean (as sulfate SO4-2)

25
KNOW SULFUR CYCLE
KNOW SULFUR CYCLE
26
What is the most abundant organic sulfur compound
Dimethyl Sulfide (DMS)
27
What can sulfur-oxidizing chemolithiotrophs oxidize in oxic/anoxic environment?
HS- (oxic) | S^0 (anoxic)
28
one of the Most abundant element and its form?
Iron Fe2+ and Fe3+ in environemnt Fe0 in human and earths core
29
KNOW IRON CYCLE
KNOW IRON CYCLE
30
Which organism oxidizes Fe2+
acidophilic chemolithiotrophs (i.e. Acidithiobacillus)
31
What form of iron and Mn is soluble and insoluble
Insoluble: Fe+3 Mn+4 Soluble: Fe+2 Mn+2
32
how does the phosphate cycle cycle?
organisms -> water -> soil
33
why is the calcium cycle important and where does it come from?
reservoirs are from rocks and oceans marine phototrophic eukaryotic microbes: i)Use Ca2+ to form exoskeleton ii)Coccolithophores & foraminifera
34
why is the silicon cycle important?
``` Build frustules 1. External cell skeletons a. Not to be confused w/ cytoskeleton b. Made of SiO2 (opal) -Uptake H4SiO4 (silicic acid) 2. Analogous to cell wall, shell, or husk ```
35
what is Hg0 photochemically oxidized to
Hg+2 (most Hg enters aquatic environments as Hg+2)
36
What two forms of mercury can microbes create?
•Microbes can form - Methylmercury (CH3Hg+) i) Extremely soluble & toxic compound - Dimethylmercury (CH3HgCH3) i) Toxic & highly volatile, can be inhaled
37
Two ways toxic Hg can be converted
``` •Toxic Hg can be converted to less toxic forms -Sulfate-reducing bacteria i)H2S + Hg2+ → HgS, low solubility -Methanogens i)CH3Hg+ converted to CH4 and Hg0 1. Hg0 is less toxic…but still toxic ```
38
know mercury cycle maybe?
know mercury cycle maybe?