1. Flow of Energy in an Ecosystem
Chapter 2 – Section 2
Flow of Energy in an Ecosystem

2. Review….. What is an ecosystem?
An area that includes all the different populations of organisms
With all of the Abiotic Factors (non living)

3. Energy Where does it come from?
The sun is the original source of all energy that organisms rely on.
We as humans may not get it directly from the sun
However, the nourishment that we take in could get it from the sun
Ex – plants take in energy from the sun, we either eat the plants or eat other animals or animal products that get energy from plants (via the sun)

4. How do we classify organisms?
We classify organisms based on how they obtain or get energy in an ecosystem.
There are 2 main types
Autotrophs
Heterotrophs

5. Autotrophs
These organisms are able to produce food (energy) on their own
They are self sufficient organisms
However they still may need other organisms for other interactions
Such as reproduction (flowers – pollination)

6. Autotrophs - types
Phototroph – use photosynthesis to produce needed energy/food
Examples:
Plants, Cyanobacteria (plant like bacteria)
Chemotrophs – use chemosynthesis to produce needed energy/food
Certain types of bacteria (some deep ocean bacteria)

7. Heterotrophs
These organisms are not able to produce food (energy) on their own, they must get their energy by consuming other organisms
Called consumers
There are 4 types of consumers/heterotrophs
Herbivores
Carnivores
Omnivores
Detritivores/Decomposers

8. Heterotrophs Herbivores – eat only plants
Cows, rabbits, many insects (but not all)
Carnivores – eat only other animals
Wolves, lions, lynx, some insects
Omnivores – eat both plants and animals
Humans, bears, some birds (but not all)
Detritivores – eat only dead materials
Worms, many aquatic organisms, some insects
Decomposers – break down dead material
Bacteria & fungi (don’t eat, they release digestive enzymes to break down food source)

9. Food Chain

10. Food Chain The Arrows represent the flow of energy.
So this means they point to the organism that eats it or obtains the energy.
They also start with autotrophs and move to heterotrophs.

11. Extra Energy
Not ALL the energy is used or passed on to the next organism in the food chain.
The extra energy is released back into the environment as HEAT.
Once extra energy (heat) is released into environment , it is no longer available for organisms to use.

12. Food Chain Each step in a food chain is also called a trophic level
First level – is made up of Autotrophs
Another way of listing this would be to call these organisms primary producers.
All following levels – are made up of heterotrophs
Second level – primary consumers
Third level – secondary consumers
Fourth level – tertiary consumers
Fifth level – quaternary consumers

13. Ecological Pyramids
Is a model that shows the relative amount of the following in an ecosystem:
Energy
Biomass
Numbers of organisms

14. Ecological pyramids
Only 10% of all energy is transferred to the next level (the level above in the pyramid)
Most of the energy that is consumed is:
Used for cellular process
Released as Heat to the environment

15. Ecological Pyramids Biomass – the total mass of living matter
Usually decreases when moved up to the next level
Relative number of organisms
Also decreases
This is because there is less energy available to support organisms.

16. Ecological Pyramid

17. Food Web
Is a model that represents many different interconnected food chains
It also represent where all the energy in an ecosystem flows (all of the paths)

18. Food Web