Ecosystems I Test II
assimilatory processes
transformations that incorporate inorganic forms of elements into the molecules of plants, animals, and microbes
dissimilatory process
involves the transformation of organic elements back to an inorganic form, accompanied by release of energy
gives up, accepts
an atom is oxidized when it _____ electroms, and reduced when it _____ them
14 billion cubic km, or 14 x 10^18g
amount of water in the biosphere
97%
more than ___ % of water in the biosphere resides in the oceans
nitrogen fixation
nitrogen enters the biological pathways of the nitrogen cycle by assimilation by certain microorganisms
ammonification
involves the breaking down of proteins into their component amino acids by hydrolysis and the oxidation of the carbon in those amino acids
nitrification
involves the oxidation of nitrogen, first from ammonia to nitrite (NO2), then from nitrite to nitrate (NO3), diring which nitrogen atoms are stripped of six, and then two more, of their electrons.
denitrification
nitrogen is reduced to nitric oxide (NO). important for breaking down OM in oxygen-depleted soils and sedients but also results in loss of nitrogen from soils because some nitric oxide escapes as a gas
sulfuric
acid that leads to acid rain and acid mine drainage
photoautotrophs
use sunlight as source of energy
chemoautotrophs
obtain energy for CO2 reduction by the aerobic oxidation of inorganic substrates like methane, hydrogen, ammonia, nitrite, hydrogen sulfide, sulfur, sulfite, or ferrous iron salts
nitrate
under anaerobic conditions in soils and sediments, certain bacteria can use _____ in place of oxygen as an oxidizing agent
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