15 Flashcards

1
Q

photosynth

A

reduction of o2

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2
Q

what are the two most dominant energy pathways in ocean

A

photosynth and respiration

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3
Q

enxymes, delta g and Ea

A

dont change delta g but decrease activation energy

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4
Q

what biological processes are highest in regions where redox species are farthest from eqm

A

euphotic zone
hydrothermal vents
sediment interface

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5
Q

N fixation by heterotrophs

A

less efficient

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6
Q

most important reducing agent in ocea

A

organic matter

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7
Q

nitrogen fixation

A

imp bc n important for growth in porteins, DNA, RNA

4/5 air is N but in unusable N2

lots of E so much be coupled w photosynth

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8
Q

what organisms couple N fixation w photosynth

A

cyanobacteria

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9
Q

global cycle

A

transfer of E through redox rxns

phototrophs transfer E from CO2 and water to oraganic c and O2 and then heterotrpohs restore reduced compounds and oxidized compounds back to their states

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10
Q

solar energy converted to

A

chemical energy

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11
Q

oxidizing agent for heterotrophs

A

organic matter bc its thermodynamically unstable in prseence of oxygen

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12
Q

small amount of co2 to organic c

A

by chemoautolithotrophs

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13
Q

where is energy derived from in the ocean

A

not from currents or heat

all from inorganic chemicals or sunlight

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14
Q

how is light absorbed

A

by chromophores that absorb uv or visible light to excite an electron that can then do rxns

form highly reactive species like superoxide or free radicals

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15
Q

free radicals

A

better oxidizing agent than o2

short half lives and limited to surface waters bc light is needed for thier formation

transient photoxidants

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16
Q

brown water

A

due to high MW humic materials that have chromophores in them

17
Q

how is superoxide formed

A

from DOM that has been photochemically excited

its O2 w electorn and neg charge

18
Q

free radical examples

A

hydroxyl radical (one extra electron)
hydroperoxyl radical HO2 w electron
O2 singlet oxygen
H202

19
Q

free radicals rxns

A

elecrophiles and react w oxygen rich species to oxidize them

20
Q

free radicals leading to oxidation

A

H202 and hydroxyl radical

21
Q

free radicals leading to oxidation and reduction

A

superoxide

22
Q

what metals are most susceptible to reaction w free radicals

A

iron
chromium
mercury

23
Q
A