Decomposers and Recycling

Decomposing Organic Material
1. Bacteria and fungi involved in decomposition feed in a different way from animals.They feed saprotrophically so they are described as sarotroph
2. Sacrotrophs secrete enzymes onto dead and waste material.
  1. These enzymes digest the material into small molecules, which are then absorbed into the organisms body.
    1. Having been absorbed, the molecules are stored or respired to release energy
3. If bacteria and fungi did not break down dead organisms, energy and valuable nutrients would remain trapped in the dead organisms.
  1. By digesting dead and waste material, microbes get a supply of energy to stay alive, and the trapped nutrients are recycled
Recycling Nitrogen within an Ecosystem
1. Nitrogen Fixation
  1. It is impossible for plants to use nitrogen directly as it is so unreactive, instead they need a supply of 'fixed' nitrogen such as ammonium ions or nitrate ions.
  2. Nitrogen fixation can occur when lightening strikes or through the Haber process. However these procceses only account for about 10% of nitrogen fixation around the world.
    1. Nitrogen fixing bacteria (Rhizobium) account for the rest.
  3. Rhizobium also lives inside the root nodules of plants of the bean family.
    1. They have a mutualistic relationship with the plant: the bacteria provide the plant with fixed nitrogen and receive glucose in return
    2. Proteins such as leghaemoglobin absorb oxygen and keep the conditions anaerobic
Nitrification
1. Happens when chemoautotrophic bacteria in the soil absorb ammonium ions

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Decomposers and Recycling

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	Created by kirareynolds over 10 years ago