B12: Organisms and their environment

  • Energy is passed on through consumption through the food chain (starting from a producer)
  • As food chains start with producers, which get energy from the Sun though photosynthesis, the principal source of energy input is the Sun


Definitions
  • Food chain: A diagram showing the transfer of energy from one organism to the next, beginning with a producer
  • Food web: A network of interconnected food chains
  • Producer: An organism that makes its own organic nutrients, usually using energy from sunlight, through photosynthesis
  • Consumer: An organism that gets its energy by feeding on other organisms
  • Herbivore: An animal that gets its energy by eating plants
  • Carnivore: An animal that gets its energy by eating other animals
  • Decomposer: An organism that gets its energy from dead or waste organic matter
  • Ecosystem: A unit containing all of the organisms and their environment, interacting together, in a given area, e.g. a lake
  • Trophic Level: The position of an organism in a food chain or food web


Transfer of energy through trophic levels
  • Energy is obtained through eating other organisms
  • There are different trophic levels where energy is passed on
  • Energy is passed on from the producer, primary consumer, secondary consumer, etc.
  • There will be less energy gained from ingestion in higher trophic levels, as only some of the energy is passed on
  • As only some energy is passed on, this means that more and more energy will be wasted throughout the trophic levels, causing the higher trophic levels to gain less energy
  • This is why food webs normally have less tahn 5 trophic levels


Interpreting a food chain diagram
  • Producers are the plants in the food chain that do not consumer other parts of the food chain, but are consumed by the primary consumers
  • The animals that consume the primary consumers are secondary consumers, with the animals eating the secondary consumers being tertiary consumers, etc.
  • The trophic levels are decided by the order of consumption in a food chain diagram
  • The producer is the first trophic level, with the primary consumers that eat the producer being the second trophic level, and the secondary consumer eating the primary consumer being the tertiary consumer


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