U1T4 - Keywords (3) Flashcards
Excretion
Removal of waste matter from an organism. (Urine)
Egestion
Removal of undigested food from an organism. (Faeces)
Nitrogen Fixation
Converts nitrogen gas into nitrogen containing compounds. Has 3 main methods (nitrogen fixing bacteria, haber process + lightning)
The Haber Process
Used to make fertilisers added to soil. Nitrogen reduced to create ammonia. Industrial method.
Nitrogen-Fixing Bacteria
Free living bacteria reduce nitrogen gas from air (air pockets in soil) into ammonia, used to synthesise amino acids for formation of proteins. Catalyse reaction with nitrogenase so it can take place at 20c unlike high temps required in Haber process. Enriches soil (farmers grow legumes + let them decay to add N2)
Ammonification
Saprobiotic bacteria/fungi feed on dead organisms/organic waste, releasing ammonia (NH4+) in water. Aided by earthworms as feed on dead organisms, breaking into small pieces (Large SA) + distributes dead material through soil.
Nitrification
Requires O2 so only occurs rapidly in well aerated soils/well oxygenated waters. 2 stages by diff nitrifying bacteria (both chemoautotrophs)
Chemoautotrophs
Derive energy for synthesis of organic molecules from oxidation reactions in nitrification.
Active Transport
Energy requiring process so proceeds best in aerobic conditions.
Leaching
When nitrates are washed out of soils due to heavy rains.
Denitrification
Denitrifying bacteria (Pseudomonas) are anaerobes + reduce nitrate (NO3-) to atmospheric nitrogen (N2) + O2 which can be used by bacteria in aerobic resp whilst N2 escapes into atmosphere. Leads to loss of nitrates from soil + can reduce soil fertility. Occurs in soils with high nitrate content but also anaerobic conditions usually caused by waterlogging.
Fossilisation
Dead organisms preserved in environments hostile to decay. (Anaerobic Conditions) Fossil fuels (coal, peat) contain locked in carbon not released as decay + decomp couldn’t occur. Carbon released by combustion.
Mineralisation
Decay + decomp by saprobiotic organisms recycling N2 in dead organisms, excreta + faeces to usable inorganic form (nitrate) 2 stages (ammonification + nitrification)
Nitrogenase
Enzyme of nitrogen-fixing bacteria that catalyses reduction of nitrogen to ammonia.
Putrifying (Decay) Bacteria
Bacteria involved in putrefaction of living matter. Recycles nitrogen from dead organisms.