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L24 - Energy in an Ecosystem

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					Energy in an Ecosystem
       Science 10
Capturing Energy From the Sun
   All living organisms require energy in
    order to support life
   The only source of energy available
    to the Earth comes from the Sun
   Therefore, this energy must be
    captured by some organisms in order
    to power life on Earth
              Ecosystem
   An ecosystem describes all of the
    organisms within a given area and
    how they interact with their
    environment and each other
   We could consider an ecosystem as
    large as the Earth or as small as a
    fish tank depending on the scale we
    wish to investigate
        Energy From the Sun
   Energy from the sun is captured by
    green plants through the process of
    photosynthesis
   Plants are able to take water from
    the Earth and carbon dioxide from
    the atmosphere and combine them
    to form sugar and release oxygen
   This process requires sunlight and
    chlorophyll
                  Producers
   Any organism that is
    able to produce its
    own food is called a
    producer
   Producers are able to
    capture energy from
    the sun through
    photosynthesis
   This energy will be
    stored in chemical
    compounds within the
    plant
          Primary Consumers
   Primary Consumers
    are organisms that
    get the majority of
    their energy from
    producers
   They are called
    herbivores
   Examples would be
    deer, rabbits and
    cows
        Secondary Consumers
   Secondary
    Consumers are
    organisms that
    feed primarily on
    primary consumers
   They are called
    carnivores
   Examples would be
    coyotes, bobcats
    and spiders
          Tertiary Consumers
   Tertiary
    Consumers are
    those who would
    feed primarily on
    secondary
    consumers
   They are called top
    carnivores
   Examples would be
    polar bears and
    eagles
                Activity
   Complete the “From Land to Mouth”
    activity on page 6
   Complete all five steps of the What
    to Do
   Answer the three What Did You
    Discover and one Extension question
                                              Energy (kJ/m^2/year)
                          ca




                                                   2000
                                                          4000
                                                                 6000
                                                                        8000
                                                                               10000
                                                                                       12000
                                                                                               14000
                                                                                                       16000




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                                                                                                               Energy Produced vs Area




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          From Land to Mouth
1.   14:1
2.   Lots of variation; due to the
     amount of the plant that can be
     consumed and growth rate
3.   Plants; more energy per given area
4.   Comparison
     a) Rice – 507m^2
     b) Chicken – 3300m^2
             Trophic Levels
   When we consider an ecosystem, it
    is often useful to consider the trophic
    (or feeding) levels within the
    ecosystem
   Most ecosystems would have four
    trophic levels although more are
    possible
              Trophic Levels
   First Trophic Level
    – Producers
   Second Trophic
    Level – Primary
    Consumers
   Third Trophic Level
    – Secondary
    Consumers
   Fourth Trophic
    Level – Tertiary
    Consumers
               Energy Loss
   10% Rule
    • This rule states that for each trophic
      level, there will be approximately 10%
      of the energy available to the next
      trophic level
   For example
    • Sun’s Energy – 1000J
    • Grass – 10J
    • Deer – 1J
    • Lion – .1J
         Pyramid of Numbers
   Since each trophic level has less
    energy available than the previous
    level, the population normally
    decreases as the trophic level
    increases
   So for an ecosystem with 100 000
    plants, there may only be 2 tertiary
    consumers
         Pyramid of Biomass
   In some cases the pyramid of
    numbers won’t work; for instance if
    you have a very large producer
    compared to the size of primary
    consumers
   This is most evident in the life that
    can be supported by a tree; one tree
    may support millions of insects
   In this case, a pyramid of biomass is
    more useful to consider
               Food Web
   We can use a web to indicate all of
    the organisms within an ecosystem
    as opposed to using a pyramid or
    food chain
          Ecosystem Activity
   Take 20 minutes and walk through
    the Urban Wilderness Park
   Identify as many living organisms as
    possible
   Classify the organisms by trophic
    level; you can include them in
    different levels if appropriate
   Create a Urban Wilderness Park food
    web
              Questions
   Page 7
    • 1-7
   Page 17
    • 1-6

				
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