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) _
Descriptions:
populations of
organisms.
& _ Abiotic (nonliving) __
inorganic nutrients,
physical features,
water, temperature,
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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Nature of 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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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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