4.3: Carbon Cycling Flashcards
Define carbon fixation. Outline the process of carbon fixation. What are the results?
Carbon fixation is the process in which inorganic carbon (carbon dioxide) is added to an organic molecule.
1) Carbon dioxide is produced by cellular respiration and diffuses out of organisms into the atmosphere and water.
2) Autotrophs absorb carbon dioxide from the atmosphere and water by diffusion and convert it to organic matter.
Intake of carbon dioxide from the atmosphere and water by autotrophs reduces the amount of CO2 in the atmosphere, particularly in areas with a large number of plants.
How can Carbon dioxide cause water to become acidic?
In aquatic habitats, carbon dioxide can dissolve into water as a gas, or it can combine with water to make carbonic acid.
Carbonic acid can disassociate to hydrogen and hydrogen carbonate ions, thus making the water acidic.
How do nutrients travel in an ecosystem?
They travel in cycles. Cycles are good examples of interaction between biotic and abiotic factors in an ecosystem.
Describe how methane enters the atmosphere.
Methane (CH4) is produced and emitted into the atmosphere by Archaean anaerobic bacteria in environments such as swamps with large concentrations of peat in the soil, landfill waste, mud along shores, the guts of termites or ruminant animals (e.g. cattle and sheep).
Explain why methane concentration in the atmosphere is not very high.
Although large amounts of methane are produced and diffuse into the atmosphere, methane concentration is not very high because it is easily and naturally oxidized to carbon dioxide and water in the stratosphere.
Define peat. Explain how it forms.
Peat is partially decomposed organic matter that has become compressed after thousands of years. It is found in waterlogged areas such as swamps, where water covers dead organic matter. the accumulation of dead organic matter becomes so acidic that aerobic decomposers are unable to fully break it down, thus forming peat.
Outline the process of fossilization.
1) Plants and animals die and sink to the bottom of the ocean.
2) The plant and animal layer gets covered with mud.
3) Over time, more sediment creates increasing pressure, compressing the dead plants and animals into oil.
4) Oil moves up through the porous rocks and eventually forms a reservoir.
Under what circumstances does fossilized organic matter combust?
If fossilized organic matter or biomass is heated to certain temperatures in the presence of oxygen, then it will combust.
What are the products of combustion? What is the reaction equation?
Carbon dioxide and water Reaction equation: fuel + O2 —–> H2O + CO2
Explain the role of limestone in the carbon cycle.
Carbon is stored in the form of calcium carbonate. This calcium carbonate makes up coral exoskeletons and mollusk shells that fossilize to become limestone. The carbon that is in limestone can be released if the limestone reacts with acid, such as carbonic acid found in rainwater.
Describe the graph of atmospheric carbon dioxide.
The graph of atmospheric carbon dioxide shows an overall increase in the concentration of carbon dioxide in the atmosphere from 1960 to 2000. There are up and down fluctuations in the graph due to seasonal oscillations in carbon dioxide concentration. The areas where the graph has an upward incline show carbon dioxide concentration in the winter, when photosynthesis is at a low: since photosynthetic activity decreases during this period, plants absorb less carbon dioxide, so the amount in the atmosphere increases. Areas of downward declines show carbon dioxide concentration in the summer, when photosynthetic activity is at a high: plants are photosynthesizing and taking up more carbon dioxide, so there is less in the atmosphere.
