Carbon Cycle Flashcards
List the major carbon reservoirs
- rock sediments
- humus
- land plants
Define commensalism
- one population benefits and the other is unaffected (co-metabolism)
Define co-metabolism
- one organism does gratuitous transformation
Define gratuitous transformation
free transformation
Define synergism
- both populations benefit (+/+)
What are the 2 elements needed for carbon cycling?
- oxygen
- hydrogen
What is humus?
mixture of organic materials from dead organic matter
Example of humus
soil microorganisms resistant to decomposition
What is the importance of land plants?
- contain large amount of ORGANIC CARBON and are major site of CO2 fixation
- relied on to pull CO2 back
What is carbon essentially cycled between?
inorganic CO2 (in atmosphere and dissolved in water) and organic compounds
What is the importance of phytoplankton
-MAJOR fixation of CO2 and generation of O2
What are methanotrophs and where are they found?
- utilize CH4 compounds
- found at interface = zone of transition of anoxic to oxic
What is the major contributor of CO2
- decomposition of dead organic material
How is carbon cycle tightly linked to O2 cycle?
- CO2 fixated (incorporated into organic compounds) by oxygen generating phototrophs that release O2
- released O2 is used for aerobic respiration for oxidation of organic matter back into CO2
What are phototrophs?
- use light as energy
- aerobic or anaerobic (purple and green sulfur bacteria)
Give an example of a phototroph
- cyanobacteria
- algae
What is oxygenic photosynthesis? give an example of what carries it out
- carried out by aquatic “higher” plants
- ex. microalgae, cyanobacteria
What is a heterocyst?
dense structure to transform
**enzyme responsible is extremely sensitive to oxygen
Define chemosynthesis and give an example
- new organic carbon from CO2 and water
- often use light as energy source
- ex. chemolithotrophs
What is respiration and where does it occur?
- organic carbon used and resynthesized = released to atmosphere
- occurs in light or dark by PHOTOTROPHIC ORGANISMS
What is the result of organic matter decomposition (2 THINGS)
- methane (via methanogens)
- CO2 via chemoorganotrophs
What is critical for organic matter decomposition?
a balance between oxidative and reductive portions of carbon cycle
What is critical in the respiration process?
- net positive balance of photosynthetic rate over respiration
Define chemoorganotroph
- attack carbon as organic source
Define methanogenesis
- formation of methane
- reduces CO2 to methane via methyl reductase
- ABSENCE OF OXYGEN
Define methanogens
- a specialized group of obligate anaerobic archaebacteria
- narrow substrate range and need to cooperate with other organisms (syntrophs)
What are methanogens critical for?
carbon transformation
- consume H2
What is the prefered habitat for methanogens
- syntrophic
- NO OXYGEN
—> swamps and marshes, often bottom of lakes - anoxic production of C cycle is carried out by cooperative organisms
In habitats with methanogens, how is the anoxic portion of the carbon cycle carried out?
- by cooperation of different groups of bacteria
- ex. degradation of organic matter under anaerobic conditions
What would happen if there was no Carbon transformation in habitats with methanogens?
lots of excess CO2
What is the state of soil that is waterlogged
anoxic - limited free O2
What is cellulolytic bacteria?
high molecular weight polymer
What is a primary fermenter? give an example
- breaks down simpler forms/compounds
- ex. glucose–>acetate and CO2
What is a secondary fermenter? give an example
- Specifically attack compounds once primary is broken down
- ex. H2 producers
What consumes H2 produced by primary fermenters? what does this do?
- methanogens
- mediates pH (avoids toxicity)
Are lignin and aliphatic saturated hydrocarbons degraded anaerobically?
No - stay intact because it requires O2 for breakdown
Define methanotroph
- subset of methylotrophs that oxidizes methane
** NOT METHANOGENS
Define methylotrophs, give an example
- 1-C compound for energy and carbon, grow because they feed on carbon
- ex. used in animal feed
What is the greenhouse effect? Give an example.
- gasses trap infrared heat from earth –> disrupts climate patterns
- ex. excess CO2 due to deforested land that could “fix” it
What are some common C1 compounds that support prokaryote growth?
- CO3
- CH4
- methanol
- Methylamine
What does pathway of CO2 assimilation =?
autotrophic CO2 fixation
How is autotrophic CO2 fixation carried out?
- Calvin cycle (aerobes)
- acetyl=CoA pathway (anaerobes)
