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BIO239 Microbiology And The Cycles Of Life > L11 Carbon Cycle > Flashcards

L11 Carbon Cycle Flashcards

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1
Q

What is sequestration

A

Release of carbon dioxide from stores

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2
Q

Where is the most global carbon
What is the issue with this

A

In the crust below the land and ocean
It is locked up and cannot be used

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3
Q

Atmospheric reservoir is low but more useful as…

A

Cycling is very quick

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4
Q

How is atmospheric carbon dioxide determined

A

Balance between fixation and release by biogenic action

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5
Q

How much carbon does burning of fossil fuels add anually

A

6 * 10^15

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6
Q

How much carbon is fixed by autotrophy each year

A

10^17 gC

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7
Q

How much carbon is taken up by oceans

A

47%

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8
Q

How much of the extra carbon produced currently remians in the atmosphere

A

A tenth

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9
Q

What risk is assocated with oceans absorbing more carbon

A

Acidification

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10
Q

What does it mean for the ocean to be saturated

A

It can’t take up / absorb any more carbon

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11
Q

What has been the change in pH since the industrial revolution (both pH and *)

A

Preindustrial pH 8.2, currently pH 8.0
PH scale is logarithmic so this is 30* increase in acidity

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12
Q

How does carbon dioxide effect pH

A

Carbon dioxide mixes with water = carbonic acid
Dissociates to bicarbonate and hydrogen
Dissociates further to carbonate and 2H+

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13
Q

What organisms will be effected by changes in calcium carbonate concentrations

A

Coral reef, bivalves, coccoliths

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14
Q

What types of calcium carbonate are more vulnerable to increasing acidity

A

Amophorous and high magnesium

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15
Q

How much carbon is stored in vegetation

A

60%

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16
Q

The amount captured in terrestrial reservoirs (trees) can be impacted by:

A

Tree type
Environmental conditions (warmer = more turnover)
Limiting nutrients

17
Q

How much carbon dioxide specifically from fossil fuels is sequested by terrestrial plants

A

10-20%

18
Q

How much carbon is sequestered in plant roots and mycorrhizal fungi

A

70%

19
Q

If hetertrophs stopped existing, how long could photoautotrophs survive

A

300 years then run out of carbon

20
Q

What are the 3 main processes in biogenic carbon cycling

A

Reduction of carbon
Aerobic oxidation of carbon
Anaerobic respiration and fermentation

21
Q

Give examples of photoautotrophs

A

Cyanobacteria
Algae
Diatoms

22
Q

Describe where an oxic habitat would form in terms of photoautotrophy and heterotrophy

A

Where action of photoautotrophy exceeds that of heterotrophy e.g. Marine photic zone

23
Q

What environments can C cycling occur with no oxygen present

A

Sub-surface rock
Aquatic sils and sediments
Waterlogged soil
Animal guts
Microenvironments

24
Q

Is anaerobic biomass accumulation faster or slower than under aerobic conditions and why

A

Slower
Because anaerobic resperiation is less efficient - terminal electron acceptor oxygen yields more energy therefore most biomass created

25
Q

Do anaerobic conditions favpur full or partial breakdown of organic matter

A

Partial

26
Q

What is radiative forcing

A

Amount of sun’s energy retained on earth compared with how much is lost to space

27
Q

How much carbon is stored in permafrost compared to the atmosphere

A

2 times

28
Q

Describe runaway climate change in terms of permafrost

A

Melting of permafrost causes warming which causes more permafrost to melt - viscous cycle

29
Q

What is the electron donor and terminal electron acceptor in methanogenesis

A

Hydrogen is electron donor
Carbon dioxide is terminal electron acceptor

30
Q

What is the role of cofactors in methanogrnrsis

A

Carry carbons from carbon diocide, removing oxygen at each step to form water

31
Q

What carries out the proton motive force in methanogenesis and why

A

Sodium channels rather than proton pumps as the hydrogen is needed to produce water

32
Q

What microbes do methanogens form a close physical association with

A

Sulphur reducing bacteria

33
Q

What is the sulphate-methane transition zone and what environments will it be found in

A

The point where the products of suphate reduction meets regions of methane produciton, can be cm or metres thick
Found in all anoxic environments

34
Q

What products of methanotrophic archaeon are scaveneged by SRB and what are they used for

A

Hydrogen or other unknown intermediates which are used as electron donors

35
Q

What is usually limiting in methane oxidation

A

Sulphate

36
Q

What utilises methane in fresh water and soil habitats

A

Gamma and alpha proteobacteria

37
Q

What is produced by prteobacteria utilising methane

A

Use monooxygenase enzyes to convert methane into formaldehyde and biomass

BIO239 Microbiology And The Cycles Of Life (12 decks)

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