1. Mrs. Nelson

2. What is Ecology?
Study of interactions
between organisms and
their environment

3. Abiotic vs. Biotic Factors
 Abiotic- “non-living” components
-ex) temperature, light, water,
nutrients, weather
 Biotic- “living” species
-ex) other organisms including
humans

4. 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
environment
 Biosphere- The entire region earth where
living things found

5. 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,
nitrogen, oxygen).

6. Living things need energy…
 Producers - organisms can do
photosynthesis
 Consumers – organisms eat other
organisms
-herbivores
-carnivores
-omnivores
-decomposers

7. Energy flow in an ecosystem
 Energy flows through an
ecosystem from the sun to
producers to consumers.

8. “Who Eats Who”…
 Food chain
- straight line pattern shows simple
feeding relationships
-illustrates passing of energy between
organisms

9. Example Food Chain …

10. “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

12. Nutrients within and
ecosystem…
 Three basic nutrient cycles are
present in all ecosystems allowing
organisms to obtain nutrients needed
to function effectively.

13. Nitrogen Cycle
 The atmosphere 80% nitrogen gas
(N2).
 However, this nitrogen can not be
used by most living things.
 Bacteria are the only organisms that
can use nitrogen directly from the
environment.

14. Nitrogen Fixation Denitrification

15. Nitrogen Cycle Terminology
 Nitrogen fixation- nitogen gas in the atmosphere
is converted to ammonia (bacteria in soil)
 Nitrification- ammonia to nitrate (bacteria in
soil)
 Assimilation- absorption of nitrate by plants
 Ammonification- break down of dead organisms
returns “unused nitrogen” to soil (bacteria and
fungi)
 Denitrification- conversion of ammonia back to
nitrogen gas (returns nitrogen to air)

16. Why is the nitrogen cycle
important?
Why is nitrogen important to
living things?
-major part of DNA and proteins
 How do plants obtain nitrogen?
-absorb it from ground
 How do we obtain nitrogen?
-eating plants

17. Water Cycle
 Driving force is sun.
 Consists of alternation between
evaporation and precipitation.
 Most water returned atmosphere
from evaporation oceans.

18. Water Cycle
Condensation
Water
Vapor

19. Water Cycle Terminology
 Evaporation- liquid water becomes gas
enters atmosphere
 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)

20. Carbon Cycle
 Carbon cycles between living
organisms and non-living components
of ecosystem.
 Carbon exists in atmosphere as
carbon dioxide (CO2).

22. 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
carbon)
 Combustion- burning of fossil fuels

23. Within an Ecosystem…
What is a community?
 All organisms in an area.
 Many interactions take place
between species.
Ex) Predator and prey

24. What if no one wins?
 In some species interactions, neither
species wins.
 Results in close, long term
associations called symbiotic
relationships.

25. 3 Kinds Symbiotic Relationships
 Parasitism (+/-)
 Commensalism (+/0)
 Mutualism (+/+)