Chapter 21

Question 1

Which CO2 is the most rapidly fixed

Answer 1

Atmosphere

Question 2

Ways that CO2 is returned to the atmosphere

Answer 2

respiration, microbial decomposition (biggest return)

Question 3

Photosynthesis Reaction

Answer 3

-CO2 +H2O –> (CH2O) + O2

Question 4

Respiration Reaction

Answer 4

-(CH2O) + O2 –> CO2 + H2O

Question 5

Two major end products of decompositio

Answer 5

-CH4 & CO2

Question 6

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

Answer 6

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

Question 7

Which two cycles are closely coupled?

Answer 7

-Carbon and NItrogen Cycle

Question 8

KNOW CARBON CYCLE

Answer 8

KNOW CARBON CYCLE

Question 9

KNOW THE COUPLED CYCLE

Answer 9

KNOW THE COUPLED CYCLE

Question 10

What is methanogenesis?

Answer 10

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

Question 11

How do methanogensis symbionts benefit the host?

Answer 11

by consuming H2 (generated from glucose fermentation)

Question 12

What is another H2 consuming process besides methanogensis?

Answer 12

Acetogenesis (less favorable)

Question 13

List the Major Nitrogen transformations

Answer 13

1. nitrification
2. denitrification
3. anammox
4. nitrogen fixation

Question 14

how is nitrogen made

Answer 14

reduction of NO3- to NH3

Question 15

what is responsible for 85% N loss

Answer 15

denitrification

Question 16

KNOW THE NITROGEN CYCLE

Answer 16

KNOW THE NITROGEN CYCLE

Question 17

What is nitrogen fixation?

Answer 17

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

Question 18

What is denitrification?

Answer 18

i) Reduction of NO3 to gaseous N products

ii) Primary way N2 is produced biologically

Question 19

Two ways NH3 can be made from N

Answer 19

1. N-fixation

2. ammonification

Question 20

what changes NH3 to N2 gas

Answer 20

Anammox-anoxic oxidation

Question 21

KNOW NITRATE REDUCTION FLOW CHART

Answer 21

KNOW NITRATE REDUCTION FLOW CHART

Question 22

Focus a lot of nitrate reduction and its various stuff

Answer 22

Focus a lot of nitrate reduction and its various stuff

Question 23

Which cycle has to most significant oxidation states

Answer 23

Sulfur (-2, 0, 6)

Question 24

Major sulfur reservoirs

Answer 24

1. sediments and rocks

2. ocean (as sulfate SO4-2)

Question 25

KNOW SULFUR CYCLE

Answer 25

KNOW SULFUR CYCLE

Question 26

What is the most abundant organic sulfur compound

Answer 26

Dimethyl Sulfide (DMS)

Question 27

What can sulfur-oxidizing chemolithiotrophs oxidize in oxic/anoxic environment?

Answer 27

HS- (oxic)

S^0 (anoxic)

Question 28

one of the Most abundant element and its form?

Answer 28

Iron
Fe2+ and Fe3+ in environemnt
Fe0 in human and earths core

Question 29

KNOW IRON CYCLE

Answer 29

KNOW IRON CYCLE

Question 30

Which organism oxidizes Fe2+

Answer 30

acidophilic chemolithiotrophs (i.e. Acidithiobacillus)

Question 31

What form of iron and Mn is soluble and insoluble

Answer 31

Insoluble: Fe+3 Mn+4
Soluble: Fe+2 Mn+2

Question 32

how does the phosphate cycle cycle?

Answer 32

organisms -> water -> soil

Question 33

why is the calcium cycle important and where does it come from?

Answer 33

reservoirs are from rocks and oceans
marine phototrophic eukaryotic microbes:
i)Use Ca2+ to form exoskeleton
ii)Coccolithophores & foraminifera

Question 34

why is the silicon cycle important?

Answer 34

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

Question 35

what is Hg0 photochemically oxidized to

Answer 35

Hg+2 (most Hg enters aquatic environments as Hg+2)

Question 36

What two forms of mercury can microbes create?

Answer 36

•Microbes can form

• Methylmercury (CH3Hg+)
  i) Extremely soluble & toxic compound
• Dimethylmercury (CH3HgCH3)
  i) Toxic & highly volatile, can be inhaled

Question 37

Two ways toxic Hg can be converted

Answer 37

•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

Question 38

know mercury cycle maybe?

Answer 38

know mercury cycle maybe?