Chapter 3.2 Energy in ecosystems Flashcards
At each level in a food chain 90% of the energy that entered that level is
not available to pass to the next level.
The energy that is lost at each level of a food chain is mainly lost as
heat and movement
At each level of a food chain some energy remains stored in
undigested material
A diagram that represents the relative numbers of organisms at each stage of a food chain is called a
pyramid of numbers
A diagram that shows the relative total masses of organisms at each level of a food chain is called a
pyramid of biomass
A diagram that shows the relative total energy in the bodies of all organisms at each level of a food chain is called a
pyramid of energy
Pyramids of biomass and energy are usually similar in
shape with a broad base representing producers, reducing to a narrow apex representing carnivores
Pyramids of number often have a similar shape to pyramids of energy and biomass but there can be differences depending on
the individual sizes of the organisms involved in the food chain.
In ecosystems the element
nitrogen is cycled
The nitrogen cycle is dependent on
various species of bacteria
Decomposers are
organisms that help to convert proteins in dead organisms and the nitrogenous waste from living organisms to ammonium compounds.
Nitrifying bacteria convert
ammonium into nitrates which can be taken up by plants
Dentrifying bacteria convert
nitrates into nitrogen gas which is released to the atmosphere.
Nitrogen fixing bacteria convert
nitrogen gas to nitrates
Some species of nitrogen fixing bacteria live free in soils and some species live in
root nodules of certain plants
