Unit A- Section 2.1

1. Unit A- Section 2.1 Energy Transfer and Food Webs

2. Out of the Total Incoming Solar • 30% is reflected by clouds or Earth’s surface • 44% heats atmosphere and Earth’s surface • 25% heats and evaporates water • 0.023% photosynthesis • 1% generates wind

3. Other sources of Energy on Earth Comes From? • Geothermal • Tidal • Waste heat from fossil fuels

4. Trophic Levels • Show the flow of energy through ecosystems- levels are categorized by how organisms GAIN energy • There are 3 trophic levels: • Autotrophs • Primary consumers • Secondary consumers Heterotrophs

5. Trophic Levels • 1sttrophic level – AUTOTROPHS (producers) • An organism that uses the Sun’s energy and raw materials to make its own food • Examples: • Plants, algae, and some types of bacteria

6. Trophic Levels • 2nd tropic level – PRIMARY CONSUMERS- rely on autotrophs for energy

7. Trophic Levels • 3rdtrophic level – SECONDARY CONSUMERS- eat animals, but rely on autotrophs

8. Energy & Food Chains • Food chains are a way of showing a step-by-step sequence of who eats whom in ecosystem • One way flow of energy (producer to consumer) • Consumers placed according to trophic level • Final carnivore is TOP CARNIVORE: not eaten by others while alive

9. Food Webs • Each individual organism in a ecosystem is involved in many food chains • The chains interlock with each other to form a feeding relationships • More complex • Most stable ecosystems with greatest biodiversity = well developed food webs- reduction of one species has only small effects • Fragile ecosystems – abiotic factors limit # of organisms- webs look more like chains- ex) Arctic • Food Webs

11. Photosynthesis & Cellular Respiration (Complementary Processes) • Photosynthesis • The process by which green plants and some other organisms use solar energy, CO2, and H2O to produce carbohydrates • CO2 + H2O + energy C6H12O6 + O2 energy stored in chemical bonds of glucose

12. Cellular respiration • The process by which cells break down glucose into CO2 and H2O to RELEASE energy • Energy is used to fuel cell processes and same is released as thermal energy • Plants produce about 9 times the amount of O2 by photosynthesis that they use up in cellular respiration • http://www.youtube.com/watch?v=pE82qtKSSH4

13. Chemosynthesis • Not all food webs begin with photosynthetic organisms • Chemoautotroph • An organism that can synthesize organic compounds from inorganic chemicals without using solar energy • Occurs in caves or deep ocean vents • Require only CO2, H2O, and an energy source • Chemical energy is extracted from inorganic chemicals such as hydrogen sulfide, ammonia, ferrous ions or sulfur

14. Ex. Banff National Park Hot spring • Bacteria convert dissolved H2S & CO2 into organic compounds which becomes food for tiny consumers • http://www.youtube.com/watch?v=XotF9fzo4Vo 6CO2(g) + 6H2O(g) + 3H2S(g)  C6H12O6(s) + 3H2SO4(g) carbon dioxide + water + hydrogen carbohydrates + sulfuric acid sulfide (sugars and starches)

15. Limits on Energy Transfer • Every time energy is transferred between the components of an ecosystem, the amount of energy available to the next trophic level is reduced • http://videos.howstuffworks.com/discovery/27995-assignment-discovery-energy-flow-video.htm

16. Laws of thermodynamics • Thermodynamics • A scientific study of energy transformations • 1st law • “energy cannot be created nor destroyed” • 2nd law • “Each time energy is transformed, some energy is lost from the system”