1. Chapter 5.1 Energy Flow in Ecosystems Environmental Science Spring 2011

2. Ojectives Describe how energy in transferred from the sun to producers and then to consumers Describe one way in which consumers depend on producers List two types of consumers Explain how energy transfer in a food web is more complex than energy transfer in a food cycle Explain why an energy pyramid is representation of trophic levels

3. Life Depends on the Sun Energy from the sun enters an ecosystem when a plant uses sunlight to make sugar molecules in a process called photosynthesis. Photosynthesis: solar drives a series of chemical reaction that require carbon dioxide and water and produce sugars (carbohydrates).

4. Life Depends on the Sun Photosynthesis equatin:

5. Life Depends on the Sun Producer: organism that makes its own food ◦Ex. Sunflower ◦Also called autotrophs Consumers: organisms that get their energy from eating other organisms ◦Ex. Deer, lion ◦Also called heterotrophs All organisms get their energy directly or indirectly from the sun!

6. Life Depends on the Sun Producer or consumer? Autotroph or heterotroph?

7. An Exception: Deep-Ocean Large communities of worms, clams, crabs, mussels, and barnacles live near deep ocean vents Exist in total darkness, photosynthesis can not occur Where do they get energy: ◦Bacteria live in some of the organisms and use hydrogen sulfide to make their own food ◦Bacteria are producers ◦Bacteria are eaten by the other underwater organisms

8. What Eats What? Herbivores: consumers that eat only producers ◦Ex. Rabbit, cow, sheep Carnivores: eat only other consumers ◦Ex. Tiger, wolf, shark

9. What Eats What? Omnivores: eat both plants and animals ◦Ex. Humans, chimpanzees Decomposers: consumers get their food by breaking down dead organisms ◦Ex. Bacteria, fungus

10. Cellular Respiration Cellular Respiration: Process of breaking down food to yield energy ◦Cells absorb oxygen and use it to release energy from food

11. Cellular Respiration Excess energy you obtain is stored as fat or sugar All living things use cellular respiration to get the energy they need from food molecules ◦Even organisms that make their own food

12. Energy Transfer Each time one organism eats another organism, a transfer of energy occurs Food chains, food webs, trophic levels ◦Trace transfer of energy

13. Food Chains and Food Webs Food Chain: a sequence in which energy is transferred from one organisms to the next as each organism eats another organism

14. Food Chains and Food Webs Food Webs: includes more organisms and multiple food chains linked together, shows many feeding relationships that are possible in an ecosystem

16. Trophic Levels Trophic Level: each step through which energy is transferred in a food chain Each time energy is transferred from one organisms to another, some of the energy is lost as heat and less energy is available to organisms at the next tropic level About 90% of energy at each trophic level is used up, remaining 10% is all that is available to next trophic level

17. Trophic Levels

18. Energy Pyramids Each layer represents one tropic level Producers: at base, lowest trophic level, contains most energy Herbivores: second level, contain less energy Carnivores: third level, feed on herbivores, contain less energy Carnivores that feed on carnivores: highest level, contain less energy

19. Energy Pyramids

20. Energy Loss in Ecosystems Because so much energy is lost at each level, there are fewer organisms at the higher trophic levels ◦Ex. 1,000 zebras for every 1 lion on African savannah ◦Must be enough herbivores to support carnivores

21. Energy Loss in Ecosytems Loss of energy from tropic level to trophic level limits the number of trophic levels in an ecosystem Organisms that feed on organisms at the top trophic level are usually small, such as parasitic worms and fleas that require small amounts of energy