Unit 2:Ecology Chapter 5: How Ecosystems Work

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Unit 2EcologyChapter 5 How Ecosystems Work

• C/S 5.1 Energy Flow in Ecosystems
• C/S 5.2 The Cycling of Materials
• C/S 5.3 How Ecosystems Change

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C/S 5.1 Energy Flow in Ecosystems

• What is the ultimate source of energy for almost
  all organisms?
• Life Depends on the Sun
• Carbohydrates are the result of what?
• Carbohydrates are the fuel for our bodies
• Where do we get carbohydrates from?
• From Producers to Consumers
• What is an autotroph?
• What is a heterotroph?
• An Exception to the Rule Deep Ocean Ecosystems
• Bacteria the live deep in the ocean make food w/o
  sunlight.
• Use hydrogen sulfide spewed out in deep ocean
  vents
• Bacteria then eaten by other organisms

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C/S 5.1 Energy Flow in Ecosystems

• What eats What
• What is an herbivore?
• What is a carnivore?
• What is an omnivore?
• What do decomposers do?
• Cellular Respiration Burning the Fuel
• During cellular respiration cells absorb oxygen
  and break down food to convert it into energy.
• Enables you to carry out your daily activities
• Help proteins repair body tissues

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C/S 5.1 Energy Flow in Ecosystems

• Energy Transfer
• In addition to telling us how the plants and
  animals in an ecosystem help each other what else
  can a Food Chain, Food Web, and Energy Pyramid
  tell us?
• Food Chains and Food Webs
• A food chain is one strand of the larger food
  web.
• Trophic Levels
• 90 of the energy at the differing trophic levels
  is used to carry out functions of daily living
• The remaining 10 is stored.
• How much is energy is transferred from one
  trophic level to the next?

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C/S 5.1 Energy Flow in Ecosystems

• Energy Pyramids
• Producers form the base of the pyramid followed
  by herbivores then carnivores.
• There is a 10 energy transfer to each level.
• How Energy Loss Affects an Ecosystem
• What are the two reasons why a decreased amount
  of energy at each trophic level affects the
  organization an ecosystem?
• How many trophic levels does an ecosystem
  typically have? why?

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C/S 5.2 The Cycling of Materials

• The Carbon Cycle
• Figure 10
• Short Term Processes
• Producers (plants) convert CO2 into carbohydrates
  via photosynthesis.
• Consumers eat producers obtain carbon from
  carbohydrates.
• Cellular Respiration
• As food is broken down CO2 is released back into
  the atmosphere
• As organisms make their own food through
  photosynthesis release CO2

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C/S 5.2 The Cycling of Materials

• Long Term Processes
• Carbon may be converted into Carbonates (the hard
  parts of bones/shells) - not quickly broken down
• Carbonate deposits gt Limestone formations gt
  Carbon Reservoir
• Carbohydrates in organisms are converted into
  fats, oils, and other molecules gt Carbon released
  into the air after organism dies gt Form deposits
  of coal, oil, and natural gas (fossil fuels)
• How do humans affect the carbon cycle?
• Cars and Factories burn fossil fuels
• Burning wood/forests release CO2 into the air
  plus eliminates a potential filter
• How much carbon is released into the atmosphere
  each year?

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C/S 5.2 The Cycling of Materials

• The Nitrogen Cycle
• Figure 12
• Nitrogen build protein used to build new cells
• 78 gas in atmosphere
• Animals get their nitrogen by eating plants or
  animals
• Stages of the Nitrogen Cycle
• Nitrogen-fixing bacteria take nitrogen from the
  atmosphere process it into a useable form that
  other organisms can use
• Nitrogen-fixing bacteria are found in the roots
  of legumes (beans, peas, clover) and in soil
• Decomposers (bacteria) breakdown wastes (urine,
  dung, leaves, animals, etc) return the nitrogen
  to the soil.
• Bacteria transforms nitrogen to Nitrogen Gas gt
  and returns to the atmosphere

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C/S 5.2 The Cycling of Materials

• The Phosphorus Cycle
• Figure 14
• Forms bones and teeth in animals
• Plants get phosphorus from soil and water -
  animals get phosphorus from plants and animals
• Stages of the Phosphorus Cycle
• Rocks erode gt phosphates dissolve into soil and
  water
• Plants absorb phosphates through their roots
• Phosphorus added to soil and water via waste from
  organisms and when organisms die and decompose.
• Phosphorus washes off land (runoff)
• Fertilizers
• Excessive amounts of fertilizer can enter
  terrestrial and aquatic ecosystems through runoff
  algal bloom
• What is an algal bloom and what can they cause?
• What is acid rain?

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C/S 5.3 How Ecosystems Change

• Ecological Succession
• Primary Succession
• Occurs where no ecosystem existed before
• Can occur on rocks, cliffs, and sand dunes
• Secondary Succession
• More common, occurs where there was an ecosystem
  previously
• Caused by human activity, and natural disasters
  (floods, storms, earthquakes, and volcanoes)
• In secondary succession a new community is first
  colonized by a pioneer species and next by a
  climax community

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C/S 5.3 How Ecosystems Change

• Fire is a natural process in ecological
  succession
• Enables new and healthy plants to grow also it
  enables animals to feed on some of the new plants
• The Jack Pine requires fire to spread its seeds
• Old Field Succession - Grasses (pioneer species)
  take over an old field to be eventually taken
  over by a climax community (such as pine/oak
  trees)
• Typically in a primary succession ecosystem the
  first species are bacteria and lichens (can live
  w/o soil)
• Lichen producer made up of fungus and algae gt
  break down the rock
• Lichen breaks down rock gt Dust collects in cracks
  of rock, Lichen and bacterial also collect in
  cracks gt Mosses begin to colonize and die and
  decay More fertile soil gt Grasses/Shrubs/Trees