1. Chapter 2 –
Principles of Ecology

2. 2.2 Flow of Energy in an Ecosystem

3. Vocabulary List autotroph heterotroph herbivore carnivore omnivore
detritivore
trophic level
food chain
food web
biomass

4. Energy in Ecosystems
One way to study the interactions within an ecosystem is to trace how energy flows through the system.
All organisms are classified by the way they obtain energy.

5. Autotrophs
Organisms that capture energy from sunlight or inorganic substances (CO2, H2O, H2S) to produce food/energy available for all other organisms in the ecosystem.

6. Autotrophs They are called PRIMARY PRODUCERS
All green plants and bacteria

7. Heterotrophs (Consumers)
an organism that obtains energy by consuming other organisms

8. A heterotroph that consumes only plants
Heterotrophs - Herbivore
A heterotroph that consumes only plants

9. Heterotrophs that prey on other heterotrophs
Heterotrophs - Carnivore
Heterotrophs that prey on other heterotrophs

10. Heterotrophs - Omnivore
Heterotrophs that consumes plants AND prey on other heterotrophs

11. Decompose organic materials in an ecosystem
Heterotrophs - Detritivores
Decompose organic materials in an ecosystem

12. How Do Detritivors Help An Ecosystem?
They feed on animals that have died:
Without them, the biosphere would be littered with dead organisms.
Return nutrients (from dead matter) to the soil, air, and water where they become available for use by other organisms.

13. Models of Energy Flow
Ecologists use food chains and food webs to describe the flow of energy
Each step in a food chain or food web is called a trophic level

14. Models of Energy Flow
Autotrophs = first trophic level in all ecosystems (produce their own food).
Heterotrophs = the remaining levels (get energy from the trophic level before it)

15. Food Chains
A simple model that shows how energy flows through an ecosystem
Each organism gets energy from the organism it eats.
The flow of energy is always one way: into the consumer
The energy can be used to build new cells/tissues or to be released into the environment

16. Food Webs Most organisms feed on more than one species.
A food web is a model that shows all the possible feeding relationships in an ecosystem.
give a more accurate picture of how energy flows in an ecosystem

17. Chapter
Principles of Ecology
Animation 2

18. Use a handout with pictures

19. Each level of the pyramid represents a trophic level.
Ecological Pyramids
Ecologists use ecological pyramids to model how energy flows through ecosystems in three different ways.
Each level of the pyramid represents a trophic level.

20. A Pyramid Of Energy
indicates the amount of energy available to each trophic level.
About 90 % of the available energy is used by the organisms at each level.
About 10 % available to the next level of the pyramid.

21. A pyramid of biomass
Biomass = total mass of living matter at each trophic
Each level shows the amount of biomass consumed by the level above it

22. A Pyramid Of Numbers
Shows the number of organisms consumed at each trophic level in an ecosystem.
The number decreases at each level because less energy is available to support organisms.

23. CLASSWORK/HOMEWORK 2.2 Reading Notes 2.2 Study Guide
MiniLAB: Construct a Food Web
Virtual lab:
NO 2.2 QUIZ

24. Possible Biomes and Abiotic Factors
How does wavelength impact a biome
How does a type of soil impact a biome
How does wind impact a biome
How does CO2 level affect impact a biome