Energy in Ecosystems

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Energy in Ecosystems

• Interactions of organisms in an ecosystem
• Food Chain one path of energy through an
  ecosystem
• Food Web- all paths of energy through an
  ecosystem, interconnected food chains.
• Ecological Pyramids are quantitative
• a) numbers of organisms
• b) biomass at each level
• c) calories of energy

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Food Chains

• Energy flows in one direction only
• Begin with a producer/autotroph
• First consumer is herbivore
• Second consumer is a carnivore or omnivore

GRASS GRASSHOPPER FROG
SNAKE HAWK
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Food Web

• Network of complex interactions.
• Feeding relationships are more complex than food
  chain.
• The more complex, the more stable the ecosystem
  will be.

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Ecological PyramidsEach trophic level is
quantitative.

• Energy pyramids show the amount of energy at each
  trophic level.
• Rule of 10 only about 10 of the energy at each
  trophic level is transferred to the next higher
  level.
• 90 of energy is used for life processes and lost
  as heat energy.

5
Biomass Pyramid

• Represents the amount of living organic matter at
  each trophic level.
• Typically, the greatest biomass is at the base of
  the pyramid.

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Pyramid of Numbers

• Shows the relative number of individual organisms
  at each trophic level
• Normally same shape as a biomass or energy
  pyramid
• Exception tree, a single tree supports a large
  number of organisms producing a diamond shape
• 1 Tree-1000 insects-10 sparrows-1 hawk

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http//www.explorelearning.com Gizmos on food
chains
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Ecology Questions

• Which of the following food chains correctly
  shows the path of matter and energy through an
  ecosystem?
• deer-bear-grass
• Grass-deer-bear
• Seeds-bear-chipmunk
• Chipmunk-seeds-deer

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2. Vegans are humans that eat only
vegetables. They do not consume meat or animal
products. How would vegans be classified? F.
Autotrophs G. Carnivores H. Herbivores J.
Omnivores
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3. A food chain always begins with a(n) F.
Herbivore G. Omnivore H. Heterotroph J. Producer
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• 4. Which ecological model shows all possible
  interactions of energy pathways that exist in a
  ecosystem?
• Food chain
• Food web
• Pyramid of numbers
• Tree of life

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• 5. Which model would an ecologist use to
• show the weight of living material in an
  ecosystem?
• A food web
• A pyramid of energy
• A pyramid of numbers
• A pyramid of biomass