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Biology Notes 2.2. Nutrition and Energy Flow Two classes of organisms when it comes to energy flow Producers: Autotrophs: Organisms that use energy from the sun or energy stored in chemical compounds to make their own nutrients Examples: Plants and some unicellular organisms
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Nutrition and Energy Flow • Two classes of organisms when it comes to energy flow • Producers: Autotrophs: Organisms that use energy from the sun or energy stored in chemical compounds to make their own nutrients • Examples: Plants and some unicellular organisms • Consumers: Heterotrophs: Organisms that can not make their own food and must feed on other organisms. • Herbivores: Feed directly on autotrophs (plants) • Carnivores: Feed on other heterotrophs (animals) • Scavenger: something that feeds on something that has already died. • Omnivores: Feed on both autotrophs (plants) and other hetertrophs (animals) • Decomposers: Break down and digest dead decaying material.
Nutrition and Energy Flow • Matter and energy Flow in an Ecosystem. • Food Chain: Simple model used by scientists to show matter and energy transfer in an ecosystem. • Uses arrows to indicate the direction of transfer. • Example: Insect Fish Bear • Most food chains have only 3 links and rarely more than five because energy is lost as heat in every exchange. • Trophic Level: Each organism in a chain that represents a feeding step. • Level 1: Autotroph • Level 2: first order heterotroph (herbivore) • Level 3: second order heterotroph (carnivores that feed on first order heterotrophs) • Level 4: Third order heterotroph (carnivore that feeds on a second order heterotroph) • Example Plant Insect Fish Eagle
Nutrition and Energy Flow • Not everything lines up in a perfect chain. A first order heterotroph may feed on several different plants. And so on This is why scientists use a Food Web. • Food Web: represents all the possible feeding relationships at each trophic level. • Ecological Pyramids: Used to show the energy flow through an ecosystem. • Energy decreases as you go up each level • The total energy transfer from one level to the next is about 10%. • Energy is lost for metabolism, growth, and as waste. • The only energy that is transferred to the next level is what was used for growth • This can also be translated into numbers of animals feed at each level. Called a Pyramid of biomass.
Example of food web Taken from: http://faculty.abe.ufl.edu/~chyn/age2062/lect/lect_28/40_07.GIF .
Example of an Ecological PyramidTaken From: http://www.bio.miami.edu/dana/160/pyramid.gif
Example of an Ecological pyramid of biomassTaken From: http://www.science.org.au/nova/039/039img/039img.gif