5.4 energy transfers within ecosystems

• in an ecosystem producers make their own food
• a plants biomass is the make up of living materials
• dry mass?

  mass of the organism with water removed
• biomass can be measured using a calorimeter
• Gross primary productivity(GPP)?

  total amount of chemical energy converted from light energy by plants, is a given area
• Net primary productivity(NPP)?

  energy available to the plant for growth and reproduction
• Net production = chemical energy in ingested food - (chemical energy lost in faeces and urine - energy lost through respiration)
• decomposers break down dead or undigested material, allowing nutrients to be recycled
• a natural ecosystem is one that hasn't been changed by human activity
• saprobionts?

  Organisms that obtain nutrients by decomposing dead organic matter.
• artificial fertilisers are inorganic- they contain pure chemicals as powders or pellets
• natural fertilisers are organic matter- they include manure, composted vegetables, crop residues and sewage sludge
• Eutrophication?

  Excessive nutrients in a body of water leading to excessive plant growth, oxygen depletion, and ecosystem disruption.
• what occurs in nitrogen fixation?

  atmospheric nitrogen turned into ammonia and then ammonium ions
• what organisms are involved in nitrogen fixation?

  nitrogen fixing bacteria
• what occurs in ammonification?

  nitrogen compounds from plants and animals gets turned into ammonia and then ammonium ions
• what organisms are involved in ammoniafication?

  saprobionts
• what occurs in nitrification?

  ammonium ions are turned into nitrites and then nitrates
• what organisms are involved in nitrification?

  nitrifying bacteria
• what occurs in denitrification?

  nitrates in soil are turned into atmospheric nitrogen
• what organisms are involved in denitrification?

  denitrifying bacteria
• when does denitrification happen?

  anaerobic conditions
• what is mycorrhizae?

  Symbiotic association between fungi and plant roots.