4.3 Carbon Cycling Flashcards
Construct a diagram of the carbon cycle
- CO2 in the atmosphere and hydrosphere (oceans)
- Carbon compounds in producers (autotrophs)
- Carbon compounds in consumers (animals)
- Carbon compounds in dead organic matter
- Carbon compounds in fossil fuels
- Respiration (used more than once)
- Photosynthesis
- Feeding
- Death
- Incomplete decomposition and fossilisation
- Combustion
What do autotrophs do with carbon dioxide?
All autotrophs convert carbion dioxide (from the atmosphere or dissolved in water) into organic compounds (carbs, lipids and proteins) mainly via photosynthesis.
How is carbon in aquatic ecosystems present
In aquatic ecosystems carbon is presented as dissolved carbon dioxide and hydrogen carbonate ions.
- Some carbion dioxide will directly dissolve in water, but most will combine with water to become carbonic acid.
- Both dissolved carbon dioxide and hydrogen carbonate ions are absorbed by aquatic plants and other autotrophs that live in water.
- H+ ions explain how carbon dioxide reduces the pH of water.
CO2 + H2O → H2CO3 → H+ + HCO3-
How does carbon dioxide from the atmosphere or water enter autotrophs?
Autotrophs convert inorganic carbon dioxide into organic compounds generally via photosynthesis.
- Carbon dioxide from the armosphere diffuses down the concentration gradient into the leaf
- Photosynthesis uses up carbon dioxide which keeps its concentration inside the leaf low
*In aquatic producers, carbon dioxide can usually diffuse directly into the autotroph; whereas in terrestrial plants, diffusion occurs at stomata
What happens to carbon dioxide produced by respiration
Carbon dioxide is produced by respiration and diffuses out of organisms into water or the atmosphere
True or false: is methane a carbon source?
True
What are methanogens?
Archaean microorganisms that produce methane (CH4) as a metabolic by-product in anaerobic conditions.
Clarification: methanogens are found IN ruminants (animals such as cows)
Examples of anaerobic conditions where methanogens may be found
- Wetlands (swamps and marshes)
- Marine sediments
- Digestive tract of ruminant animals (cows)
From the by-products of what do methanogens produce methane
Anaerobic respiration
- Typically during ATP production methane is formed
- Principaly from aceteic acid or carbon dioxide (+ hydrogen)
What is peat and how is it formed?
Peat is organic matter that is not fully decomposed.
- This occurs in anaerobic conditions (like in waterlogged soils) when sapotrophic bacteria can not function effectively.
Coal formation
When peat is compressed under layers of sediment, heat
and pressure remove moisture to transform it into coal
Oil/Natural gas formation
Oil and natural gas form as the result of the decay of marine organisms on the ocean floor.
- When these marine organisms die they are buried in the ocean floor and covered by layers of sediment.
- After millions of years, the heat and pressure turns them into oil and gas.
Combustion soruces which produce carbon dioxide
- Fossil fuels
- Biomass (bioethanol, biofuels)
What is made from calcium carbonate?
and limestone
CaCO3
- The shells of molluscs and the exoskeletons of hard corals are made of calcium carbonate
- When the animals die the soft body parts decompose, but the shells of skeletons form deposits on the ocean floor.
- The deposits are buried and compressed and
eventually form limestone
Conditions should be slightly alkaline
- Imprints of the hard body parts remain in the
rock as fossils.
Lithification
The process of compressing organic matter over a long period of time until it becomes rock.
