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DO NOW 9/29/14
• Where does the energy you obtain from
eating a salad and a burger go?
OBJECTIVES
• SWBAT explain how ecological efficiency
works by participating in an activity.
• SWBAT set-up and implement an experiment
to demonstrate ecological efficiency.
• SWBAT define biomass and describe how a
food chain/web works in terms of biomass.
VOCABULARY
• Decomposer
• Detrivore
• Trophic level
• Biomass
• Ecological efficiency
ENERGY TRANSFER IN
ECOSYSTEMS
Photosynthesis
THE RECYCLING MACHINES
• Decomposer:
• An organism that digests parts
of dead organisms, cast-off
fragments, and wastes of living
organisms, and returns nutrients
to the environment.
• E.g. bacteria and fungi.
DETRIVORES
Detrivores: Insects or
other scavengers that
feed on waste or dead
bodies.
Convert complex organic
chemicals into simpler
inorganic nutrients that
can be taken up by
producers.
FOOD CHAIN
• Trophic
level: the
position in the
food chain or
web an
organism
occupies
FOOD WEB
RELATIONSHIP BETWEEN
BIOMASS AND ENERGY
• Biomass is dry weight of a plant and represents
the chemical energy stored at each energy level.
• Water is neither a source of energy, nor has any
nutritional value.
ENERGY FLOW IN AN ECOSYSTEM:
LOSING ENERGY IN FOOD CHAINS
AND WEBS
• Ecological
efficiency:
percentage of
useable energy
transferred as
biomass from
one trophic
level to the next.
ECOLOGICAL EFFICIENCY:
THE 10% RULE
• On average, only 10% energy is transferred
across trophic levels
• Some is lost as heat; some used up by the
organism
Man, this meal will last me
30 minutes…Going to have
to find more after.