1. Nutrient Cycling Water Cycle: Repeated movement of water between the earth and the atmosphere Water is essential to life The water cycle has four steps Evaporation (liquid to gas = water vapor) Transpiration (water vapor released from plants) Condensation (gas to liquid = raindrops) Precipitation (Occurs when gravity pulls water droplets from clouds; rain, snow, hail)

2. Nutrient Cycling Carbon Cycle: Repeated movement of carbon between the earth’s atmosphere and living things All living things are made up of carbon Found as CO2 in the air CO2 is removed from the air by producers and used to make glucose (photosynthesis) which is then eaten by consumers CO2 is released into the air by producers and consumers (cellular respiration – when you exhale) and by decomposers who break down dead and decaying materials

3. Nutrient Cycling Nitrogen Cycle: Repeated movement of nitrogen between the earth’s atmosphere and living things All of the proteins that make you who you are contain nitrogen Found as N2 in the air- makes up 78% of the air N2 needs to undergo “nitrogen fixation” by bacteria so that it becomes a form of nitrogen usable by plants Plants use the nitrogen to build proteins that are passed on when the plants are consumed When plants and animals die decomposers and bacteria break the nitrogen down once again and return some to the soil and some to the air