Energy Flow in Ecosystems & The Biosphere
Slide # 2
Important Vocabulary
1. Ecology: study of the
relationships among
organisms & between
organisms & their physical
environments.
2. Population: all members of
a species living in a given
location
3. Habitat: place where an
organism lives
4. Community: all the
interacting populations in a
given area
1. Give an example of a
population.
2. Give an example of a
community.
Slide # 3
Important Vocabulary
5. Ecosystem: all members of
a community & the physical
environment in which they live
a. Biotic factors: all living things
b. Abiotic factors: all non-living
things such as:
– Temperature, precipitation,
sunlight, soil, salt content, pH
6. Biome: large, stable groups of
ecosystems that share the same
biotic and abiotic factors
7. Biosphere: portion of earth in
which all living things exist
Earth’s biosphere
includes all biomes,
the atmosphere, the
lithosphere, &
hydrosphere (oceans
& lakes).
Slide # 4
Ecological Levels of Organization
Smallest
Largest
Individual  Population  Community  Ecosystem  Biome  Biosphere
Go to
Section:
Slide # 5
Flow of Energy in an Ecosystem
Decomposers
Sunlight  Producers  Consumers
1. Trophic level: each level of
energy flow
2. Producers (autotrophs):make
own food from energy source
a. Photosynthesis: plants &
algae; transform light energy
into chemical energy
b. Chemosynthesis: some
bacteria use chemical energy
in inorganic molecules or heat
as energy source
Slide # 6
Consumers: Depend on Other Organisms for Food
3. Consumers: organisms
that cannot make own food
a. Get energy by eating producers
& other consumers
b. Primary consumers: eat
producers
• Herbivores: plant eaters
c. Secondary consumers: eat other
consumers
• Omnivores: eat plants &
animals
• Carnivores: eat only animals
4. Decomposers: obtain energy by
breaking down the remains of dead
organisms
Identify the different
types of consumers!
Principle Decomposers:
Decomposers
Obtain energy from the
remains of other
organisms
*Bacteria
*Fungi
Must know!
Earthworms and termites aid in the breakdown of organic
matter, which replenishes nutrients to the soil.
Slide # 7
A Marsh Food Web
5. Identify examples of the
different trophic levels in the
marsh ecosystem at the right.
a. Producers:
b. Primary consumers:
c. Secondary consumers:
d. Decomposers
Go to
Section:
Slide # 8
Food Chains Show the Transfer of Energy
10,000
kcal
1,000
kcal
100
kcal
10
kcal
1. Food Chains: show the transfer of energy through a series
organisms – ENERGY FLOWS IN ONE DIRECTION!
2. 10% rule: typically only 10% of the energy at one level is
transferred to the next level
a. Energy is used by organisms for cell processes,
respiration, capturing prey, and reproduction
b. Explains why most food chains don’t have more than 4
or 5 trophic levels
Slide # 9
Food Webs Show Interconnected Food Chains
1.All food chains in a
community interconnect to
form one food web.
2.A change in population of
one organism can affect all
other organisms in the
food web.
3.Arrows point in the
direction of energy flow.
– Energy flows in one
direction!
Which organisms would
be affected if all of the
wolves were removed
from the food web?
Slide # 11
Ecological Pyramids: Show the Amount of
Matter or Energy in an Ecosystem
1. Pyramid of numbers:
shows how many
individuals are required
to support the next level
of feeding.
2. Usually does not
illustrate the actual
amount of organism
mass (stored energy)
that is transferred
through each feeding
level.
6 birds
1,000,000 insects
1 tree
An inverted numbers pyramid
Slide # 12
Energy Pyramid: Total Energy Available at Each Level
1. Energy pyramid: shows
amount of energy
available at each level
2. Shows that about 90%
of the energy is lost as
heat ~ 10% is
transferred to the next
level
Slide # 13
Biomass Pyramid: Total Living Material at Each Level
1. Biomass: amount of
living tissue
2. Gives the amount of
living tissue at each
trophic level
3. Represents the
amount of food
available in each
trophic level in an
ecosystem.
Slide # 15
The Water Cycle
1. Water enters atmosphere by:
– Transpiration : trees
releasing water through
leaves
– Respiration: animals
exhaling water
– Evaporation: from surface
water
2. Precipitation: water returns to
Earth in the form of rain, snow,
hail, & sleet
3. Groundwater: water that seeps
into the ground
4. Run off: water that runs off the
surface
Surface & ground water may run into
oceans, lakes & rivers and streams
Slide # 16
The Carbon Cycle
1. In photosynthesis, producers
remove CO2 gas from the
atmosphere to make organic
molecules (sugars)
2. Animals get organic molecules
from plants & return CO2 gas to
the atmosphere through
respiration.
3. Fossil fuels, (Coal, oil, natural
gas) were once living organic
material. When they are
burned, CO2 gas is returned to
the atmosphere and increases
the amount of CO2 gas in the
air.
Slide # 17
The Nitrogen Cycle
1. Nitrogen fixation: actions by
some bacteria & lightning
change N2 gas into forms
(NH4+ and NO3-).
2. Plants absorb these forms
through their roots.
3. Herbivores obtain nitrogen
from the plants they eat.
4. Decomposers break down
animal waste, dead animals,
& dead plant material &
return the nitrogen to the soil.
Other bacteria return
nitrogen in the soil back
to the atmosphere.
Slide # 14
TAKS Practice
How much energy would be
available to the organisms in
level C?
A. all of the energy in level A,
plus the energy in level B
B. all of the energy in level A,
minus the energy in level B
C. a percentage of the energy
contained in level B
D. a percentage of the energy
synthesized in level B and
level D
An energy pyramid is
represented below.
Which way does energy flow in
an ecosystem?
From sun to producers
(base) to consumers (above).
Which level has the most
energy? A
Which level has the least
energy? D
Correct answer: C
TAKS Practice
The mouse population would most
likely decrease if there were
A an increase in the grass
populations
B a decrease in the snake and
hawk populations
C an increase in the number of
decomposers in the area
D a decrease in the amount of
available sunlight
Correct answer: D; mice eat grass which
depends on sunlight for photosynthesis
What does this diagram show?
Food Web