Monday, May 9, 2011

4.5 understand the concepts of food chains, food webs, pyramids of number, pyramids of biomass and pyramids of energy transfer

Food chain: In order of rank, a series of organisms each dependent on the next as a source of food.

Food webs: In an ecosystem there are many different food chains & many of these are cross-linked to form a "food web."

Pyramids of number:  The Number pyramid shows the number of organisms in each trophic level + the higher up it goes, there are fewer organisms than the level below it.

 Biomass Pyramid:  This pyramid indicates the total mass of the organisms in each trophic level.The total biomass at a particular step in a food chain is always less than the total biomass at the step before it.

Pyramid of energy transfer:  The Energy pyramid indicates the total amount of energy present in each trophic level. It also shows the loss of energy from one trophic level to the next.

An energy pyramid shows clearly that the energy transfer from one trophic level to the next is accompanied by a decrease due to waste and the conversion of potential energy into kinetic energy and heat energy.

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