Energy Transfer

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  • Created by: Max123
  • Created on: 18-03-13 21:35
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Some of the energy fixed within organic molecules by autotrophs (producers) is transferred to other organisms in an ecosystem.
Heterotrophs are organisms that obtain energy as `ready-made' organic matter by ingesting material from other organisms. They cannot make
their own food; instead they consume it, depending on autotrophs for their food.
Primary consumers (herbivores) eat plant material.
Secondary consumers (carnivores) feed on primary consumers.
Tertiary consumers (also carnivores) eat other consumers.
Energy is transferred from producers all the way to tertiary consumers. These feeding relationships are shown in food chains or food webs. The
position a species occupies in a food chain is called the trophic level.
NOT ALL THE ENERGY GETS TRANSFERRED TO THE NEXT TROPHIC LEVEL ­ around 90% of the total available energy is lost in various ways.
Some of the available energy (60%) is never taken in by organisms:
Plants can't use all the light energy that reaches their leaves e.g. some is the wrong wave length, some is reflected and some passes
straight through.
Some parts of food e.g. roots or bones, aren't eaten by organisms so the energy isn't taken in.
Some parts of food are indigestible so pass through organisms and come out as weight e.g. faeces. For example, mammals have no
enzymes that are capable of breaking down cellulose.
The rest of available energy (40%) is absorbed ­ the GROSS PRODUCTIVITY. However this is not all available to the next trophic level either.
30% of the total energy available is lost to the environment when organisms use energy produced from respiration for movement or body
10% of total energy available becomes BIOMASS ­ the NET PRODUCTIVITY ­ this is the amount of energy available to the next trophic


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