chapter 3 how ecosystems work
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CHAPTER 3 How Ecosystems Work. The Sun. The sun is the main source of Energy for all life on earth. The sun is the start of most food chains. Less than 1% of the sun’s energy that reaches earth i s used by living things. CHAP. 3-1 Energy Flow. Feeding Relationships: - PowerPoint PPT PresentationTRANSCRIPT
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CHAPTER 3 How Ecosystems Work
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The Sun
• The sun is the main source of Energy for all life on earth.
• The sun is the start of most food chains.• Less than 1% of the sun’s energy that
reaches earth is used by living things.
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CHAP. 3-1 Energy Flow
• Feeding Relationships:• Autotrophs – get energy from sun or
chemicals to produce food (photosynthetic or chemosynthetic); also called producers
• Heterotrophs – depend on autotrophs or other heterotrophs for food; also called consumers
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Types of Heterotrophs• Herbivores – feed only on
plants; ex – rabbits, deer• Carnivores – feed only on animals
ex. – tigers and lionsOmnivores – feed on plants & animals ; ex. –
bears, humans
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Types of Heterotrophs
• Detritivore- feeds on detritus (dead matter)– Scavengers – feed on dead organisms; ex. –
vultures, crayfish– Decomposers – feed on dead or decaying plant &
animals; ex. – bacteria, protozoa, fungi
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Feeding Relationships• Food Chain - Model to show how
matter & energy flow through an ecosystem
• Energy must 1st pass from producers to consumers
• Food chains only show 1 possible • route
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Feeding Relationships• Food webs – show all possible routes• Each organism
represents a feeding step or trophic level
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Trophic LevelsEach step in a food web or food pyramid
is called a trophic level (energy level)
10% RuleOnly 10% of the energy from one
trophic level is passed on to the next.100% grass 10% cow 1% humans
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Levels of Consumers
• Primary consumers– Eat producers
• Secondary consumers– Eat herbivore
• Tertiary consumers– Eat carnivore
• Quaternary consumers– Eats carnivore that ate the carnivore
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Ecological Pyramids
• Diagram that shows the amounts of matter or energy contained at each trophic level
• 3 pyramids:• Pyramid of Energy• Pyramid of Numbers• Pyramid of Biomass
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Pyramid of Energy• Shows the amount of energy which is
moving from one level to the next.• Shows that only
about 10% of theenergy available within a trophiclevel is transferredto the next trophic level
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Pyramid of Numbers• Shows the
decreasingnumber oforganismsat each successivefeeding level
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Pyramid of Biomass• Biomass- total amount of living tissue in a given trophic level.• Shows the amt. of potential
food at each feeding level; decreases at each successive level
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Biomagnification
• The tendency for the concentration of pollutants to increase in animals higher up on the food chain.
• Ex: mercury in Tuna, or DDT in Eagles
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3-3 Succession• Succession: Changes in an ecosystem over time; include organisms dying out & new ones taking their place
• Pioneer species – the 1st species to populate the area
• Climax Community- the community that eventually forms if the land is left undisturbed.
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Primary Succession• Primary succession – occurs on surfaces
where no soil existed; ex. – after a volcano erupts
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Secondary Succession• Secondary succession – follows a disturbance
that destroyed an ecosystem but did not destroy the soil; ex. – after a forest fire