B7 Further Biology 2013

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  • Created by: emma
  • Created on: 11-06-13 17:10


Closed loop systems are where any waste produced in that system is useful for something else, for example excess reproductive structures are eaten by organisms.

Most systems arent perfect closed loop systems and have extra inputs and outputs involved.

Ecosystems are examples of closed loop systems because their waste is reused:

  • Faeces, dead plant matter, fruits are eaten by microorganisms
  • Oxygen is a waste product produced by plants, this is used by animals for respiration
  • Carbon dioxide is a waste product by animals, which is used by plants for photsynthesis
  • Mineral nutrients (e.g. nitrogen) are produced by microorganisms which are used when theyre absorbed by plants
  • large quantities of reproductive structures like sperm, eggs, pollen are produced which are eaten by other organisms


Stable ecosystems

Some ecosystems lose their outputs sometimes

  • Dead organic matter is carried out the ecosystem by wind or water
  • Some animals migrate and dont stay in the ecosystem

These outputs are balnced by gains

  • Rainforests lose lots of water as it all drains into rivers and is carried away, however this is balanced out by heavy rainfall.
  • Large amounts of vegetation is produced in stable ecosystems, vegetation reduces soil erosion (where soil is washed or blown away) and prevents extremes of temperatures. Vegetation also promotes cloud formation.


Human Impacts

Humans can take out large amounts of outputs in ecosystems, for example over -fishing has meant that cod has become endangered, or deforestation in the rainforests in South America have meant habitats have been lost.

Humans can also put in large amounts of inputs which unbalances ecosystems e.g. farmers add lots of fertilsier…


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