biologia

  • A trophic level consist of all the organisms in an ecosystem which feed in the same way 
There are three types: 
•producers 
Autotrophic organisms that perform photosynthesis and use solar energy to transform inorganic matter into organic matter 
•consumers 
Heterotrophic organisms that eat other living thingns:
   *primary consumers: feed on producers ,   they are herbivores (rabbits,deers)
   *secondary consumers: feed on primary consumers (frogs feed from insects)
   *terciary consumers: feed con secondary consumers (they are lions, tigers…)
•decomposers
Heterotrophic organisms that obtain their nutrientes by decomposing dead organisms(like bacteria por fungi)
  • A trophic chain or food chain , is a diagram that uses arrows and drawings to show the organisms in the different trophic levels of an ecosystem and their feeding relationship
  • Trophic networks or food networks are representations of the different trophic chains in an ecosystem and the connections between them
  • the transfer of matter :

1.Producers create organic matter

Producers take inorganic matter(carbondioxide,water and mineral salts)and transform it into organic matter, to build and repair their bodies

2.Organic matter passes though the trophic levels

Organic matter is transfered to the primary consumers when they eat them, then to teh secondary consumers. Consumers use this organic matter to build an repair their bodies.

3.The organic matter returns to the environtment

When organisms die, decomposers feed on them and transform organic remains into products that return to the environtment and are used by the producers.

  • the transfer or energy: 

1.Producers capture part of the solar energy

Most of the energy ecosystem receive comes from the sun. They only use a part of it to perform photosynthesis, light energy is transformed into chemical energy and stored in the organic matter they produce

2.What happens to the energy captured by producers

The energy is passed throught food, most of the energy is consumed by metabolism and some more is realised in form of heatin each trophic levels.



  • Trophic parameters

These parameters allo us to asses the matter and energy that accumulates at each trophic level and which passes from one level to another.

  • Biomass

 Biomass is the amount of organic matter created in each of the trophic levels of the ecosystems and that can be used as a resource of energy.

According to which organisms produce the organic matter we can classify them into :

   *Primary biomass: produced by autotrophic organisms (by photosynthesising organisms)

   *Secondary biomass: produced by heterotrophic organisms (by animals,fungy…)

   *Terciary biomass: formed as a result of a tipe of human activity

      1.primary in origin such as sawdust (serrin)

      2.secondary such as manure and urban waste

  • Production is an increase in the biomass of an ecosystem, or of one of the trophic levels, per unit of surface of area, or volume, and per unit of time. A measurement of the amount of energy that accumulates in the ecosystem or in each trophic level.
  • primary production is the amount of light energy stablished as prymary biomass by photosynthesising organisms; in other words thw amount of light energy transformed into chemical energy by sinthesising organisms.
  • Gross primary production represents the food that is available for heterotrophic organisms. Is the amount of organic matter (biomass) synthesised by the autotrophic organisms per unit f time, including that consumed by respiratio`n, the metabolism and reproduction.
  • Net primary production is the organic matter that remains after deducting respiration.
  • Secondary production is the amount of energy that has been stored in the tissues of heterotrophic organisms. it can also be classified into gross and net production.
  • Gross secondary production is the percentage of the total amount of food consumed that is assimilated.
  • Net secondary production is the energy that remains available for the following trophic level. 


  • Ecological pyramids or trophic pyramids, are graphs that give a simplified version of the trophic relationships between the organisms of a biological community and allow us to quantify biomass, the energy available and the number of individuals in the community.
  • Energy piramids show the energy available in each trophic level (8,8 kcal available /m2 X year)
  • Biomass pyramids provide information about organic matter accumulated in each trophic level per unit of surface area at a specific tim (100g/m2)
  • Number pyramids are those with steps that are proportional to the number of individuals found in an ecosystem, per unit of surface are, or biotope volume at a specific time.
  • Biochemical cycle is the circulation of chemical elements though the atmosphere, the hydrosphere, the geosphere and the biosphere, which makes this elements available over and over again.

Two types of biochemical cycles :

     * gaseous nutrient cycles: the atmosphere is the main reserve of the element. The main cycles of this type are the oxygen,carbon and nitrogen cycles.

     * sedimentary nutrient cycles: the main deposit of the element is the lithosphere, most significant, sulfur and phosphorous cycles.

The carbon cycle can be sumarised as two sub-cycles:

     *The short cycle: living things capture an d transform the CO2 that is found in the atmosphere and disolved in the hydrosphere :

^Producer use photosynthesys to “set” CO2 in the organic matter that they create. Consumers and decom`posers incorporate this carbon into their bodies through  the food chain.

^When organisms respire, and when they die an decomposers ant on their orgamic matter, most of the carbon returns to the environtment and becomes available to the producers again

     *The long cycle: related to the carbon stored in fossil fuels, limestone, the wood in trees, and inside the earth. This carbon can return to the atmosphere after millions of years:

^When the fuel is extracted and burnt in industry, it releases CO2 into the atmosphere.

^When limestone undergoes a weathering process.

^When the woog from trees is burnt.

^ In volcanic eruptions that spew out carbon from inside the earth.