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what are saprotrophs?
organisms such as bacteria and fungi that feed on dead and decaying matter
what happens during the process of decay?
saprotrophs secrete enzymes which digests the material into small molecules which are then absorbed by diffusion or active transport, they are then stored or respired
what are the 4 processes involved in the nitrogen cycle?
ammonification, nitrification, denitrification and nitrogen fixation
what is ammonification?
the production of ammonium ions from nitrogen containing organic compounds in dead matter or faces
what are 4 nitrogen containing organic materials?
nucleic acid, proteins, urea and amino acids
what is the word equation for ammonification?
nitrogen containing organic material —> ammonia —> ammonium ions
what is the symbol equation for ammonification?
nitrogen containing organic material —> NH3 —> NH4+
what is nitrification?
the conversion of ammonium ions to nitrite ions and then nitrate ions by nitrifying bacteria
what are nitrifying bacteria and example of?
chemoautotrophic bacteria
how do chemoautotrophic bacteria obtain their energy?
oxidation reactions in the soil
what are the conditions for nitrification?
aerobic
what are the 2 types of nitrifying bacteria involved in nitrification?
nitrosomonas and 2. nitrobacter
what is the word equation for nitrification?
ammonium ions —> nitrites —> nitrates
what is the symbol equation for nitrification?
NH4+ —> NO2- —> NO3-
what is dentrification?
the conversion of soil nitrates into gaseous nitrogen by anaerobic denitrifying bacteria
what type of reaction is denitrification?
reduction reaction
what is the word equation for denitrification?
nitrate —> nitrogen
what is the symbol equation for denitrification?
NO3- —> N2
what is nitrogen fixation?
the conversion of nitrogen gas into nitrogen containing compounds
what are the conditions for nitrogen fixation?
anaerobic conditions
what type of reaction is nitrogen fixation?
reduction reaction
what are the two types of bacteria involved in nitrogen fixation?
free living and mutualistic
what is the name for free living nitrogen-fixing bacteria?
azobacter
what is the name for mutualistic nitrogen-fixing bacteria?
rhizobium
what do free-living nitrogen-fixing bacteria do?
reduce gaseous nitrogen into ammonium which they then use to make amino acids
where do you find mutualistic nitrogen-fixing bacteria?
in root nodules of leguminous plants
what do mutualistic nitrogen-fixing bacteria do?
reduce gaseous nitrogen into ammonium ions which they give to the plant in exchange for carbohydrates
what conditions are these root nodules?
anaerobic
what keeps the root nodules anaerobic?
proteins such as leghaemoglobin
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