Understanding Energy Flow in Ecosystems

1. Ch 5 How Ecosystems work

2. Energy in Ecosystems • What is the source of energy for most ecosystems? • The sun! • What kingdom of organisms use this energy first ON LAND? • Plants • What kingdom of organisms use this energy first IN WATER? • Protists: Algae • Phytoplankton: small, mostly microscopic, photosynthesizing algae that drift in the lighted part of aquatic ecosystems • Phyto = plant or plant-like • Plankton = remainder of above definition

3. Energy Flow in Ecosystems • What is the process plants and phytoplankton use to produce their own food, using energy from the sun? • Photosynthesis • What “food” does photosynthesis produce? • Glucose, a simple sugar, C6H12O6 • What gas do plants use for photosynthesis? • Carbon dioxide (CO2)

4. Energy Flow in Ecosystems • What else do autotrophs need for photosynthesis? • water • What gas is released as a waste product of photosynthesis? • Oxygen (O2) • So, putting it all together, photosynthesis • CO2 + H2O  O2 + C6H12O6 • Balancing the reaction, we get • 6CO2 + 6H2O  6O2 + C6H12O6 • What powers this reaction? • The sun!

5. Energy Flow in Ecosystems • What do we call organisms that make their own food? • Autotrophs • Another term? • Producers • These make up the base of the food chain for all other organisms in an ecosystem

6. Energy Flow in Ecosystems • What types of organisms are most of the producers on land? • Plants • What types of organisms are most of the producers in water? • Phytoplankton

7. Energy Flow in Ecosystems • Why do we say the sun powers most (not all) of the ecosystems on earth? • Deep ocean vent communities have autotrophic archaebacteria that use energy from hydrogen sulfide.

8. Energy Flow in Ecosystems • So… producers form the basis of energy of all ecosytems • Energy is transferred through ____________ • Eating/consumption • What types of organisms do the consuming? • Consumers! – duh!, or heterotrophs • What had to come first?The autotrophs or heterotrophs? • Autotrophs, because heterotrophs had to have something to eat!

9. Energy Flow in Ecosystems • What process do consumers use to break down the sugars in plants and release the stored sun energy from them? • Cellular respiration • 6O2 + C6H12O6  6CO2 + 6H2O • The exact opposite of photosynthesis

10. Energy Flow in Ecosystems • Every time a consumer consumes, it gets only 10% of the original energy of the organism it consumed • So, _________ % is lost with each step along the way • Producers get 100% of the sun’s energy • The organisms that eat producers, ____, get only 10% of that sun’s energy • Herbivores, 1st level consumers, primary consumers • What do we call human herbivores? • Vegetarians

11. Energy Flow in Ecosystems • Organisms that eat the primary consumers are called • Secondary consumers • Another ___ % of the sun’s energy is lost in the transaction • So, secondary consumers only get ____ % of the original sun’s energy • 1 %  (that’s us, when we eat beef, chicken or pork)

12. Energy Flow in Ecosystems • Some secondary consumers can also be primary consumers. How? • They eat plants and animals; i.e. steak and salad • Organisms that eat both plants and animals are called • Omnivores

13. Energy Flow in Ecosystems • At the top of the food chain are organisms that consume only other consumers • These are called • Carnivores • Top carnivores are usually few and far between in an ecosystem because there isn’t enough of the sun’s energy left to go around at that level

14. Energy Flow in Ecosystems • Third level, or _______ consumers, get only ___% • .1%   of the sun’s energy that went to the producers in the ecosystem • Most ecosystems cannot support more than 4 or 5 trophic levels • Organisms that feed on organisms at the top level are usually small and need small amounts of energy, like • Decomposers, or parasites like fleas

15. Energy Flow in Ecosystems • So…, the more producers in an ecosystem, the more of the sun’s energy can be absorbed • And the more ___ can be supported by the producer level • consumers • All food chains start with ___ • producers

16. Energy Pyramid What’s missing in this picture?

17. Energy Flow in Ecosystems Each level of consumerism is called a TROPHIC LEVEL

18. Food chain vs. food web • Food chains show one path of energy from the sun to the last consumer (decomposer) • Food webs show the many interconnected paths of energy through an ecosystem • The arrows represent ____________________ • Energy transfer from one organism to the next

19. Food Chain vs. Food Web Food web- complex flow of energy made up of many food chains Food chain- straight line flow of energy