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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.

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Presentation on theme: "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."— Presentation transcript:

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 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.

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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  Biomass  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.


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