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5.4 nutrient cycles - Coggle Diagram
5.4 nutrient cycles
lesson 2: nitrogen cycle (detailed)
1) inert nitrogen gas in the atmosphere
2) nitrogen fixation by nitrifying bacteria in the soil or in root nodules
3) proteins in nitrogen fixing bacteria
4) ammonification/ release of ammonia by nitrogen fixing bacteria
5) ammonium ions in the soil
6) nitrification by nitrifying bacteria - oxidation of ammonium to nitrite ions and then the oxidation of nitrite ions to nitrate ions
7) nitrate ions are absorbed and assimilated into proteins in plants
8) consumers eat the plants - proteins in animals
9) egestion and excretion (face and urine) and death :
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lightning causes reaction between oxygen and nitrogen in the air resulting in nitrate ions
3) proteins in plants (legumes)
4) death
5) proteins in dead organic materials/urea in urine
6) decomposition and ammonification by saprobints
nitrogen fixation
nitrogen gas converted to nitrogen containing compounds
occurs through nitrogen fixing bacteria or when lightning causes reaction between oxygen and nitrogen
ammonia only released to the soil when bacteria die and decompose
free-living nitrogen fixing bacteria
convert gaseous nitrogen to ammonia which they then use to make amino acids
found in the soil - nitrogen rich compounds released when they die
mutualistic nitrogen fixing bacteria
live in the nodules on the roots of plants
obtain carbohydrates from the plant and plant requires amino acids from the bacteria
decomposition and ammonification
ammonification = production of ammonia from organic nitrogen-containing compounds e.g. proteins/nucleic acids
saprobiontic microorganisms feed on faeces and dead organisms materials, releasing ammonia which forms ammonium ions in the soil - nitrogen returns to the non-living components of the ecosystem
nitrification
conversion of ammonium ions to nitrate ions
oxidation reaction (releases energy)
carried out by nitrifying bacteria in two stages: 1) oxidation of ammonium to nitrite ions, 2) oxidation of nitrite ions to nitrate ions
oxygen is required (exist in a well aerated environment)
denitrification
conversion/reduction of soil nitrates into gaseous nitrogen
caused by anaerobic denitrifying bacteria
reduces the availability of nitrogen-containing compounds In plants
lesson 1: nitrogen cycle (intro)
role of saprobionts (decomposers)
e.g. fungi and bacteria
feed on dead or organic material
carry out extracellular digestion
returns nutrients back to the soil
nitrogen
component of
ATP
nucleic acids (DNA and RNA)
proteins/amino acids
but nitrogen in the atmosphere is chemically inert and not able to be used by most organisms
plants
plants must secure their nitrogen in 'fixed' form i.e. incorporated in components such as: nitrate ions, ammonia
basic pattern of nutrient cycling
nutrient taken up by producers
assimilated into complex organic molecule
passes into consumers through food chains and along/up trophic levels
released during breakdown of dead organic matter and saprobiontic microorganisms
simple form of nutrient returned to non-living state
lesson 3: fungi and fertilisers
mycorrhizae