1. Ecology – the study of how organisms fit into their environment Ecosystem – Organisms and their physical environment Community – A group of organisms that live in a particular place Habitat – the physical location a community lives in Population – a group of organisms of the same species There are many POPULATIONS in a COMMUNITY. The COMMUNITY lives in a HABITAT. A COMMUNITY of organisms and their HABITAT make up an ECOSYSTEM. The more populations in an ecosystem, the more diverse it is.

2. Producers – use the sun’s energy to make food Consumers – obtain energy by consuming other organisms Decomposers – obtain energy by consuming organic wastes

3. Water Cycle!

4. Nitrogen Fixation Nitrogen-fixing bacteria in plant roots Ammonia NH3 Decomposition Soil Bacteria Nitrogen gas in the atmosphere

5. Nitrogen Cycle Nitrogen is found in 2 of the 4 molecules needed for life – proteins and nucleic acids Plants get nitrogen by way of nitrogen-fixing bacteria in the soil. The bacteria are able to convert nitrogen into forms other organisms are able to use. Ammonia produced by bacteria can be used by plants. Nitrogen in plants moves to consumers by consumption. Decomposers break down dead animals and nitrogen is put back into the soil.

6. Photosynthesis Cellular Respiration Death and Decomposition Fossil Fuels Combustion Carbon Dioxide in atmosphere

7. Carbon Cycle Consumer eats plant. Digests plant body. This releases carbon atoms and energy. Energy is used by consumer. Some carbon is added to consumer’s body. Other carbon atoms are exhaled as CO2. Decomposers break down dead consumer’s bodies. Use some of the carbon atoms to build themselves up. Return other carbon atoms to atmosphere as CO2.

8. SYMBIOSIS DIRECT relationship between 2 different species (NOT PREDATOR-PREY relationship) ( +, - ) PARASITISM – a parasite lives on/in/near it HOST parasite gets an advantage (food, blood, safety) Host is harmed (usually slow, can be life ending eventually) ex: Tapeworm, leech, salmonella ( +, + ) MUTUALISM – both creatures get a benefit ex: Clownfish in an anenome ( +, 0 ) COMMENSALISM – one creature benefits, the other is neutral ex: Barnacles on a whale, hair mites in YOUR hair

10. Trophic Levels: 3rd Level and up: carnivores, omnivores heterotrophs (do NOT make their own food) Smaller population 2nd Level: herbivores heterotrophs 1st Level: autotrophs (make their own food) The 10% Rule: –Each level gets 10% of the energy from the level before –The rest of the energy Is lost to heat!