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12 Cards in this Set
- Front
- Back
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Nitrogen defieicieny in plants leads to |
, loss of chlorophyll giving a white colour stunted growth |
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Basics of the nitrogen cycle |
nitrification denitrification nitrogen fixing ammonification |
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Nitrogen fixation |
Atmospheric nitrogen represents about 78% of total N2 in atmosphere is vary stable, has triple bond Large amounts of energy needed to fix it this reaction requires 18-24 ATP molecules |
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What enzymes causes nitrogen fixation and in what organisms does it exist |
nitrogenase complex Has 2 components 1) Dinitrogenase 2) Dinitrogenase reductase Occurs in: Aerobes and anaerobes Symbiotic microbes with plants, the most important |
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Nitrogen fixation and relationship with oxygen |
Oxygen inactivates nitrogenase enzyme complex Aerobic N-fibres protect the dinitrogen reductase by rapidly removing oxygen by respiration Some organisms have O2 impermeable slime layers Some have proteins that forms a complex with any free oxygen - 'protector proteins,' Some have cellular partitions |
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What are the specialised nitrogen fixing compartments presents in some cyanobacteria? |
heterocysts given nutrients by neighbouring cells oxygen free environment maintained |
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Denitrification |
Major loss of usable nitrogen to ecosystem Anarboic process NO3 used as electron acceptor, releasing nitrogen to atmosphere Multi step process Repressed by O2 |
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Dinitrifcation process |
Nitrate is the starting point Nitrogen lost to atmosphere in the form of: NO nitric oxide N20 nitrous oxide N2 Dinitrogen |
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Ammonification |
Decomposition of organic Nitrogen (mainly proteins) Process releases ammonia Process is both Aerobic and Anaerobic Aerobic is by fungi Nitrogen lost by NH3 gas (15%) Amonium ion NH4+ (85%) |
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Nitrification |
Conversion of Ammonia to nitrate Common in aerobic soils Important process The nitrate (NO3) produced is highly soluble, allowing many organisms to use it Solubility also allows leaching, a possible problem |
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Fertiliser |
In agriculture ammonium added in fertliser Inhibitor of nitrification added The inhibitor increases the efficiency of fertilisation The inhibitor also decreases run-off and algal blooming |
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nitrification organisms |
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