1. ENERGY FLOW IN ECOSYSTEM How does energy flow in an ecosystem? How does energy flow in an ecosystem? What is a trophic level? What is a trophic level?

2. ENERGY ENTERS ECOSYTEM All energy in ecosystem comes from the sun First law of Thermodynamics: Energy cannot be created or destroyed (but it can be transformed into stored energy & heat)

3. ENERGY LEAVES ECOSYSTEM Second law of thermodynamics: Some Energy is lost when it is transformed Second law of thermodynamics: Some Energy is lost when it is transformed In ecosystems, when energy is transformed, some energy is lost as HEAT In ecosystems, when energy is transformed, some energy is lost as HEAT

4. ENERGY PATHS 3 ways to illustrate energy flow 1. Food Chain: Single path 2. Food Web: many paths3. Food Pyramid

5. FOOD CHAINS A food chain shows the path of energy from one organism to the next. Each level is called a TROPHIC LEVEL ( A food chain shows the path of energy from one organism to the next. Each level is called a TROPHIC LEVEL (Troph = feed) energy flows from producers to consumers energy flows from producers to consumers arrows mean “ is eaten by ” (plant is eaten by herbivore) arrows mean “ is eaten by ” (plant is eaten by herbivore) Usually decomposers are left out Usually decomposers are left out

6. FOOD CHAINS AND WEBS Practice! Draw a food chain that includes the following organisms: Practice! Draw a food chain that includes the following organisms: grasshopper grasshopper mouse mouse grass grass owl owl Now label the organisms as producers, consumers (which type?), or decomposers Now label the organisms as producers, consumers (which type?), or decomposers PRODUCER CONSUMER (HERBIVORE) CONSUMER (CARNIVORE)

7. FOOD WEBS A food web shows all feeding relationships in an ecosystem (made of many food chains) A food web shows all feeding relationships in an ecosystem (made of many food chains)

8. FOOD WEBS Typically, food webs go like this: Typically, food webs go like this: PRODUCER CONSUMER (HERBIVORE) CONSUMER (CARNIVORE) CONSUMER (OMNIVORE) DECOMPOSER remember: decomposers receive energy from all other organisms in an ecosystem remember: decomposers receive energy from all other organisms in an ecosystem

9. FOOD CHAINS/WEBS & PYRAMIDS (ENERGY; NUMBERS & BIOMASS) Food chains/webs can be written as a pyramid: Food chains/webs can be written as a pyramid: Producers form the base of the pyramid Producers form the base of the pyramid Consumers form the upper layers Consumers form the upper layers http://www.harcourtschool.com/activity/science_up_close/314/deploy/interface.html Pyramid of numbers

10. ENERGY PYRAMIDS Top Consumer Energy stored by Secondary Consumers Energy stored by Primary Consumers ENERGY STORED BY PRODUCERS The energy pyramid shows energy flow in an ecosystem: How efficient is the transfer of energy among organisms in an ecosystem?

11. Energy is lost with each trophic Energy is lost with each trophic ~90% is released to the environment as heat ~90% is released to the environment as heat ~10% of the energy is used ~10% of the energy is used

12. Energy is lost with each trophic Energy is lost with each trophic ~90% is released to the environment as heat ~90% is released to the environment as heat ~10% of the energy is used ~10% of the energy is used Only about 10% of the energy from one level is passed on to the next level

13. QUICK REVIEW Practice! If 100% of the energy is available at the first trophic level, what percentages of the energy are available at the second and third trophic levels? Practice! If 100% of the energy is available at the first trophic level, what percentages of the energy are available at the second and third trophic levels? 100% 10% 1%

14. Copyright Pearson Prentice Hall 3–2 The main source of energy for life on Earth is organic chemical compounds. inorganic chemical compounds. sunlight. producers.

15. Copyright Pearson Prentice Hall 3–2 How does a food web differ from a food chain? A food web contains a single series of energy transfers. A food web links many food chains together. A food web has only one trophic level. A food web shows how energy passes from producer to consumer.

16. Copyright Pearson Prentice Hall 3–2 The amount of energy represented in each trophic level of consumers in an energy pyramid is about 10% of the level below it. 90% of the level below it. 10% more than the level below it. 90% more than the level below it. http://www.youtube.com/watch?v=pSwnjhIeX1w