What is Ecology?
Study of interactions
between organisms and
Abiotic vs. Biotic Factors
Abiotic- “non-living” components
-ex) temperature, light, water,
Biotic- “living” species
-ex) other organisms including
Levels of Ecological Organization
Species- organisms can interbred and
produce fertile offspring
Population- all members of a species in area
Community- every species in area
Ecosystem- all organisms and physical
Biosphere- The entire region earth where
living things found
Conditions for Life
In order for an ecosystem to sustain life, several
conditions must be met:
1) Energy source (ex: sun)
2) Living organisms convert energy to organic
molecules (ex): Plants –photosynthesis)
3) Nutrients must move between organisms and
the environment (ex: water, carbon dioxide,
Living things need energy…
Producers - organisms can do
Consumers – organisms eat other
Energy flow in an ecosystem
Energy flows through an
ecosystem from the sun to
producers to consumers.
“Who Eats Who”…
- straight line pattern shows simple
-illustrates passing of energy between
“Who Eats Who”…
Food web- illustrates how all the
food chains in an ecosystem related
“Network of feeding relationships”
Keystone species- species that
affects many other species and can
not easily be replaced if lost
Nutrients within and
Three basic nutrient cycles are
present in all ecosystems allowing
organisms to obtain nutrients needed
to function effectively.
The atmosphere 80% nitrogen gas
However, this nitrogen can not be
used by most living things.
Bacteria are the only organisms that
can use nitrogen directly from the
Nitrogen Cycle Terminology
Nitrogen fixation- nitogen gas in the atmosphere
is converted to ammonia (bacteria in soil)
Nitrification- ammonia to nitrate (bacteria in
Assimilation- absorption of nitrate by plants
Ammonification- break down of dead organisms
returns “unused nitrogen” to soil (bacteria and
Denitrification- conversion of ammonia back to
nitrogen gas (returns nitrogen to air)
Why is the nitrogen cycle
Why is nitrogen important to
-major part of DNA and proteins
How do plants obtain nitrogen?
-absorb it from ground
How do we obtain nitrogen?
Driving force is sun.
Consists of alternation between
evaporation and precipitation.
Most water returned atmosphere
from evaporation oceans.
Water Cycle Terminology
Evaporation- liquid water becomes gas
Transpiration- loss water from plants
Water vapor- water atmosphere (gas)
Condensation- process where water
molecules gather atmosphere “change from
gas to liquid”
Precipitation- water falls atmosphere to
ground (rain, snow, hail, etc)
Carbon cycles between living
organisms and non-living components
Carbon exists in atmosphere as
carbon dioxide (CO2).
Carbon Cycle Terminology
Photosynthesis- PLANTS use sunlight,
carbon dioxide and water to make sugar
Respiration- process organisms use oxygen
and release carbon dioxide back into air
Fossil fuels- dead organisms buried in
sediment change to coal or oil (unused
Combustion- burning of fossil fuels
Within an Ecosystem…
What is a community?
All organisms in an area.
Many interactions take place
Ex) Predator and prey
What if no one wins?
In some species interactions, neither
Results in close, long term
associations called symbiotic