Energy Flow
How does energy move
through the ecosystem?
http://www.armofthesea.info/images/landscapes/crommet_lg.jpg
Conservation:
• Law of Conservation of Matter – In any ordinary physical or chemical
change, matter is neither created nor
destroyed, only transformed from one
form to another.
• Law of Conservation of Energy – In any ordinary physical or chemical
change, energy is neither created nor
destroyed, only transformed from one
form to another.
Energy:
• 2nd Law of Thermodynamics:
–When energy is changed from
one form to another, some
energy will be lost to the larger
environment.
• Nothing is ever 100% efficient.
• This is due to entropy (nature’s tendency
towards randomness).
How does energy flow through
ecosystems?
• Food Chain: A simple diagram of one string of
feeding relationships in an ecosystem, showing
the direction of the transfer of energy in that
system.
Sun
Grass
Rabbit
Soil
Wolf
Bacteria
What are the parts of a food chain?
Producers
• Organisms that make their own food from
inorganic molecules and energy.
– eg. Plants, blue-green algae
Energy through
is
–Inorganic
Most accomplish energy building
almost always
Molecules
=
photosynthesis
from the sun
molecules that are
• H20 + Sunlight + CO2  Sugar
+ Orare
2
(very
not part of
a living
exceptions)
organism
Consumers
• Organisms that cannot make own
food.
– eg. all animals, fungi and most bacteria
– Obtain energy by eating other organisms
— through a process called cellular
respiration
• Sugar + O2  CO2 + H20 + energy
Decomposers
• Bacteria and fungi
that break down
organic material
Decomposers are
essential to
ecosystem health
because they recycle
nutrients back for
producers to reuse.
Food Web:
• a group of
food chains
showing all of
the feeding
relationships
in an
ecosystem.
Food Web
Sun
Human
Wolf
Sheep
Rabbit
Grass
MiceDeer
Flower
Fox
Bacteria
Carrots
Nutrient Rich Soil
Biological Magnification
• Increasing concentration of a substance
in the tissues of organisms in the higher
levels in a food chain or web. (Nearly
always something dangerous, like a toxin)
Many
toxins in
the water
Many
toxins in
the
person
• Biological
Magnificationaccumulation of
increasing amounts of
toxin within tissues of
organisms.
Video on Biological
Magnification
Food Webs con’t:
• Trophic level — a
layer in the feeding
relationship of an
ecosystem, one link
in the food
chain/web.
• Biomass — total
amount of organic
material present in a
trophic level.
So, all producers are
at the same trophic
level and all primary
consumers are at the
next trophic level.
Organic = is
currently living or
lived in the past
Energy Pyramids
http://www.vtaide.com/png/foodchains.htm
http://www.earthforce.org/files/1284_image2_Energy_Pyramid_for_
Galvbay.jpg
• Another way to look at
trophic levels.
• a diagram showing the
relative amounts of
energy/biomass in the
different trophic levels.
• Lowest trophic levels
are at the bottom:
Producers have the
greatest biomass.
Example of an Energy Pyramid
1 MAN
MAN
0.1%
10%
100 %
of the
sun’s
energy
FOX
1%
10%
10%
RABBIT
Rabbit
90%
Energy Lost
during
conversion
to heat,
waste….
90%
10%
Grass
90%
10 FOXES
100
RABBITS
1000
Bunches of
GRASS
- The decreasing size of the pyramid shows
that each level of the pyramid has a smaller
and smaller number of those organisms.