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
What is the Biosphere?
All forms of life on Earth are connected in a
biosphere
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Ecology Terms
Organism living thing
Population groups of living things
Communitygroup of populations
Ecosystemgroup of communities
Biome Group of ecosystems
Biosphere Group of biomes
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There are two main components of an
ecosystem:
Biotic (living)
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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Biotic Interactions
Organisms occupy a specific role, or niche, in an environment
•Competition  fight between individuals or species for
food/habitat/mate
•Predation  action where a hunter feeds on prey
•Symbiosis  situation where 2 organisms interact with
each other and both benefit from this interaction
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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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• 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: tree  giraffe  lion
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Food chain
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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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The Phosphorus Cycle
The phosphorus cycle is a sedimentary cycle.
Only limited quantities are made available to
plants by the weathering of sedimentary
rocks; phosphorus is a limiting inorganic
nutrient.
The biotic community recycles phosphorus
back to the producers, temporarily
incorporating it into ATP, nucleotides, teeth,
bone and shells, and then returning it to the
ecosystem via decomposition.
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The phosphorus cycle
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Changes to Ecosystems
Air Pollution  Burning of fossil fuels
releases CO2, SO2, and NO2,NO3 into
atmosphere. Results in climate
change, acid rain, damage to ozone
layer
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Habitat Destruction
• Over past 50 years, 50% of tropical
forests have been cleared for timber or
farmland (deforestation)
• Loss of habitat often means extinction
for organisms within that habitat
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Invasive Species
Introduction of species to new habitats,
usually by humans
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