Ecology Review
Living things do not live in vacuums, their daily
lives are based on interactions with both living
and nonliving things.
What is an ecosystem?
Groups of organisms and
their physical environment
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There Are Two Main Components Of An
Ecosystem:
Biotic -Living
Populations of
organisms.
temperature,
&
Abiotic-Nonliving
Inorganic nutrients,
physical features
water,
and wind.
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Biotic Components: A Closer Look
Autotrophs are producers that produce food for
themselves and for consumers.
How do autotrophs make food?
Photosynthesis and chemosynthesis
Heterotrophs are consumers that take in premade
food.
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Biotic Components
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Consumers Vocabulary:
Herbivores – animals that eat plants
Carnivores – animals that eat other animals
Omnivores – animals that eat plants and animals
Decomposers - bacteria and fungi, that break
down dead organic waste.
Detritus - partially decomposed organic matter in
the soil and water; beetles, earthworms, and
termites are detritus feeders.
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Consumers
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Consumer Levels
Primary consumer – an organism that gets its energy
from plants (producers)
Secondary consumer – an organism that gets its
energy from primary consumers
Tertiary consumer – carnivores that eat other
carnivores; a top-level consumer, usually the top
predator in the food chain
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Energy Flow
What is energy flow?
The movement of energy through the organisms
in an ecosystem
What direction does energy flow through an
ecosystem?
Sun  Producers  Various levels of
consumers
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Energy Flow
As energy flows from autotrophs (producers) to
heterotrophs (consumers) much of the energy is lost
before the consumer can use it.
In what forms is energy lost?
Heat
Initial energy from an ecosystem comes from a
consistent supply of solar energy
Remember energy in an ecosystem may be
transferred or converted but will not be created nor
destroyed
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Energy Balances
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Energy Flow in an Ecosystem
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Food Chains vs. Food Webs
What is a food chain?
A diagram that links organisms together by who eats whom
Starts with plant life and ends with an animal.
Most food chains have no more than 4 or 5 links
Arrows show the direction energy is flowing
EXAMPLE: grass  zebra  lion
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Food chain
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FOOD WEB
Most consumers feed on and are eaten by more than
one other consumer
What is a food web?
A combination of several food chains showing all
of the possible energy pathways
What is a trophic level?
All of the organisms that feed at a particular link of
the food chain/web
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Food Webs
Grazing food web –
The upper portion of a food web based on a
living plant as the producer
Detrital food web –
The lower portion of a food web based on
detritus
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Forest Food Webs
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Ecological Pyramids
Why are food chains so short?
Only about 10% of energy is useable from one trophic
level to the next
The number organisms drastically decreases as you go up
in level of a food chain
What is an ecological pyramid?
A series of blocks representing the biomass of particular
organisms on a particular trophic level
What is biomass?
The amount of living material in the population of an
organism
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Ecological Pyramid
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Biochemical cycles
What are biochemical cycles?
The path by which important nutrients/molecules
travel through an ecosystem.
3 Important Cycles:
Water Cycle
Carbon Cycle
Nitrogen Cycle
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The Water Cycle
Water movement:
Land  Atmosphere:
Liquid  Gas
Evaporation from rivers, lakes
and oceans
Transpiration from plants
Atmosphere  Land
Gas  Liquid
Precipitation over land and bodies of water
Runoff forms bodies of water (lakes, rivers,
oceans)
Ground water seepage into aquifers
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The Water Cycle
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The Carbon Cycle
Carbon Movement:
Land/Water  Atmosphere
Respiration
Combustion
Atmosphere Land/Water
Photosynthesis
Dissolved CO2
** Carbon is stored as fossil fuels from decaying
organisms.**
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The Carbon
Cycle
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The Nitrogen Cycle
Nitrogen Movement:
Nitrogen Fixation  Bacteria found in legume roots
converts N2 gas into Ammonia (NH4)
Decomposers break down waste and organic remains into
Ammonia (NH4)
Nitrification  bacteria convert ammonia into Nitrite
(NO2) and Nitrate (NO3) to be used by plants
Denitrification  Bacteria converts ammonia back into
Nitrogen gas (N2)
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The Nitrogen Cycle
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