BRAINCAKENutrient Cycles
Revision notes for Nutrient Cycles in AQA Biology (7402). Read the start of any lesson here, then sign in free for the whole lesson, the R.E.C.I.P.E. recall steps and the quiz.
- Nutrient CyclesEnergy flows through an ecosystem and is eventually lost as heat, but chemical elements such as carbon, nitrogen and phosphorus are recycled.
- Role of SaprobiontsSaprobionts (also called saprotrophs) are microorganisms, mainly bacteria and fungi, that obtain their nutrients from dead organic matter and from…
- The Nitrogen CycleNitrogen is needed to make amino acids (and so proteins) and nucleotides (DNA, RNA and ATP).
- Nitrogen FixationNitrogen fixation is the conversion of nitrogen gas (N2) from the atmosphere into ammonia (NH3), which forms ammonium ions (NH4+) in solution.
- AmmonificationAmmonification is the production of ammonia from organic nitrogen-containing compounds by saprobionts.
- NitrificationNitrification is the conversion of ammonium ions (NH4+) into nitrate ions (NO3−) by nitrifying bacteria.
- DenitrificationDenitrification is the conversion of nitrate ions (NO3−) in the soil into nitrogen gas (N2), which returns to the atmosphere.
- The Phosphorus CyclePhosphorus is needed by all organisms to make ATP, nucleic acids (DNA and RNA) and phospholipids in cell membranes.
- MycorrhizaeMycorrhizae are associations between certain fungi and the roots of plants.
- Natural and Artificial FertilisersIn a natural ecosystem, minerals taken up by plants are returned to the soil when organisms die or produce waste and saprobionts decompose them.
- Effects of Fertilisers on ProductivityProductivity is the rate at which plants produce biomass.
- LeachingLeaching is the process by which nutrients are removed from the soil.
- EutrophicationEutrophication is the process by which nutrients build up in a body of water, leading to an increase in the growth of algae and, eventually, the…