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Chapter 5How Ecosystems Work

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Section 1Energy Flow in Ecosystems

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Energy Flows in EcosystemsMost organisms

depend on the sun for energy.

Producers get their energy from the sun through photosynthesis and then consumers eat those producers.

Photosynthesis:6 CO2 + 6 H2O (+ sunlight) C6H12O6 + 6 O2 (+ energy)

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Producers are also called autotrophs.

Consumers are also called heterotrophs.

An autotroph can make its own food.

Most autotrophs use photosynthesis to get their energy.

Some autotrophs use chemosynthesis to get their energy like the ones that live in deep-ocean ecosystems.

A heterotroph gets its energy by eating others.

A heterotroph breaks down the food it eats and turns it into energy through cellular respiration.

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What eats whatHerbivores eat only plants.Carnivores eat other consumers.Omnivores eat both.Decomposers break down dead

organisms.

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Each step in a food chain is called a trophic level.

FOOD CHAINS FOOD WEBS

Are a linear sequence showing how energy is transferred from one organism to another

Show the many feeding relationships that are possible in an ecosystem

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Energy PyramidsProducers form the

base of the pyramid.

Energy is lost as you move up the pyramid.

Only 10% of the energy goes to the primary consumers, secondary consumers, and tertiary consumers.

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That is all for 5.1Time for quiz 1.

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Section 2The Cycling of Materials

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Matter cycles through an ecosystem.Carbon cycles between the

atmosphere, land, water, and organisms. Carbon is the essential component of life.

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Humans affect the carbon cycle

By burning fossil fuels and cutting down trees.

This could lead to climate change.

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The Nitrogen CycleNitrogen is

cycled between the atmosphere, bacteria, and other organisms.

Bacteria plays a very important role in nitrogen fixation and denitrification.

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Nitrogen cycle could not happen without bacteria!

NITROGEN FIXATION DENITRIFICATION

When bacteria converts nitrogen gas into ammonia or some nitrate.

When bacteria converts ammonia or nitrate back into nitrogen gas.

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The Phosphorus CycleIs the process of

moving phosphorus from the environment to organisms then back to the environment.

It happens when rocks erode or ocean sediment makes it back to land.

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Human affect the phosphorus cycleExcess use of

fertilizers leads to accelerated eutrophication

Burning coal leads to acid precipitation

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That’s all for 5.2Time for quiz 2

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Section 3How Ecosystems Change

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Ecological SuccessionIs the gradual process of change

and replacement of some or all the species in a community.

The hardwood trees show the climax community when all factors are in balance.

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There are two types of successionPrimary happens

when there is no life or soil intact.

Examples: Glacier retreats or volcano erupts.

Secondary happens when there is some life or soil intact. Examples:Old-field succession that occurs after farmland is abandoned, floods and forest fires.

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Pioneer SpeciesAre the first organisms to

colonize an area and begin the process of ecological succession

Lichens are an example of pioneer species.

They break down the rock and begin the formation of soil.

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That is all for 5.3Time for quiz 3.