1. 1. Review- Energy is said to flow in a “one-way stream” through an ecosystem. In your own words, describe what that means Form a Hypothesis- Explain what you think might happen to the food chain on pg 65 if there were a sudden decrease in the number of crayfish 2. Review- On average, what proportion of the energy in an ecosystem is transferred from on trophic level to the next, where does that energy go Calculate- Draw an energy pyramid for a five step food chain. If 100% of the energy is available at the first trophic level, what percent is available at the highest trophic level

2. 3.3 Energy Flow in Ecosystems
Ch 3 The Biosphere
3.3 Energy Flow in Ecosystems

3. What happens to energy stored in body tissues when one organism eats another
Energy moves from the “eaten” to the “eater.” Where it goes from there depends on who eats whom.

4. Food Chain Diagrams that shows what eats what
Arrows point from food source to what eats it
Arrow shows flow of energy
Series of steps in which organisms transfer energy by eating and being eaten.

5. Food Web Combination of all the food chains in the community
Arrows point from food source to who eats it.

7. Decomposers and Detritivores
Most producers die without being eaten
Decomposers convert that dead material to detritus, which is eaten by detritivores
Decomposition process releases nutrients.

8. Food Webs and Disturbance
All of the animals in this food web depend directly or indirectly on krill- zooplankton
In recent years, krill populations have dropped substantially.

9. Trophic Levels and Ecological Pyramids
Energy Pyramids
Show the relative amount of energy available at each trophic level
Biomass Pyramids
Illustrates the relative amount of living organic matter at each trophic level
Numbers Pyramids
Shows the relative number of individual organisms at each trophic level in an ecosystem.

10. Trophic Levels Each step in a food chain or food web
Primary producers always make up the first trophic level
Various consumers occupy every other level.

11. Pyramids of Energy Each level passes on roughly only 10% of the energy
Organisms expend much of the energy they acquire on life processes, such as respiration, movement, growth, and reproduction
10 Percent Rule
Only 10% of the energy at any given level is available for use by organisms in the next higher level
What do you like to eat
What would be the best for humans to eat.

12. Pyramids of Energy

13. Pyramids of Biomass and Numbers
Total amount of living tissue within a given trophic level
Usually greatest biomass and numbers are at the base of the pyramid
Size of pyramid depends on amount of energy available.