Unit 3.2: EcosystemsChapters 3 & 4

Anchor: BIO.B.4.2: Describe interactions and relationships in an ecosystem◦ BIO.B.4.2.1: Describe how energy flows through

an ecosystem

Standards

For life to continue within the ecosystem, three things must be present

◦ 1. The SUN ultimately provides nearly all energy on earth!

◦ 2. The cycling of both matter and nutrients.

◦ 3. Gravity helps to hold everything in place, including the atmosphere and helps to move nutrients through their cycles

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Fungi

All things in an ecosystem can be classified as:◦ Biotic: anything living (or once living)

Ex:◦ Abiotic: anything nonliving (never alive)

Ex:

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Classification of Organisms◦ Producers/Autotrophs: make their own food,

usually through photosynthesis Ex:

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Chemosynthesis: producers create food in the absence of light using hydrogen sulfide◦ Ex: bacteria that live at deep sea vents

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Consumers/Heterotrophs: cannot make their own food◦ Herbivores: feed on

plants/producers Also called primary consumers Ex:

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◦ Carnivores: feed on other animals Secondary Consumers: feed on

primary consumers Ex:

Tertiary Consumers: feed on secondary consumers Ex:

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◦Omnivores: eat both producers and consumers Ex: raccoon, bears, rats

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◦ Detritivore Consumers: feed only on DETRITUS Detritus: parts of dead organisms, wastes of

organisms Ex: earthworms, crabs, ants

◦ Decomposers: break down organic matter so that it can be recycled Ex. Bacteria, fungi

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How does energy MOVE through ecosystems?◦ Energy moved in the form of “food” or organic

matter◦ Remember, energy can only flow in ONE direction

From the sun producers consumers

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Food chain: a series of steps where organisms transfer energy by eating and being eaten◦ Ex:

◦ What are the limitations of a food chain? Very simple/limited – doesn’t show all food

connections in an ecosystem

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Food Webs: multiple linked food chains demonstrating the complex interactions in communities◦ Ex:

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Trophic Levels: each step in a food chain or web◦ Ex:

Producers = 1st trophic level Consumers = 2nd, 3rd, 4th trophic levels

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Fig 6.3

© 2005 John Wiley and Sons Publishers

Fig 6.4

© 2005 John Wiley and Sons Publishers

Fig 6.5

© 2005 John Wiley and Sons Publishers

Fig 6.6

© 2005 John Wiley and Sons Publishers

Trophic Levels: ◦ Each consumer depends upon the trophic level

below it for all energy! Only 10% of the energy is transferred from level to

level The other 90% is used by the organisms for metabolism

(respiration, movement, reproduction, growth) and given off as body heat

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sun

secondary consumers(carnivores)

primary consumers(herbivores)

producers (plants)

loss of energy

loss of energy

loss of energy

What happens to all the energy?

only this energymoves on to the

next level in the food chain

17%growth

50%waste (feces)

33%cellularrespiration

energy lost todaily living

energy lost todaily living

Ecological Pyramids: illustrate the relative amounts of energy or matter contained within each trophic level

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1,000,000,000

100,000

100

1

Numbers

Energy Pyramids: illustrates the amount of energy (organic material), usually in kCals or Joules (J), available

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Biomass Pyramids: illustrates the total amount of living tissue in a trophic level, usually in g/unit area

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Numbers Pyramid: illustrates the actual number of individual organisms in each trophic level

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