3.4 Cycles of Matter

1. -Matter cannot be created or destroyed, it changes. -biological processes-all activties performed by living organisms (breathing, “burning” food, & eliminating waste products) -geological processes-volcanic eruptions, formation & breakdown of rock, & major movements of matter. 3.4 Cycles of Matter

2. -chemical & physical processes-formation of clouds & precipitation, the flow of running water, & lightning. -Human activity-mining & burning of fossil fuels, clearing of land for building & farming, burning of forests, & the manufacture & use of fertilizers.

3. The Water Cycle -water molecules enter the atmosphere as water vapor when they evaporate from the ocean or other bodies of water or by evaporating from leaves (transpiration) -if this air cools, water vapor condenses into tiny droplets that form clouds. When the droplets become large enough, they fall to the Earth's surface as precipitation (rain, snow, sleet or hail)

4. -on land, some precipitation flows along the surface (runoff) until it enters a river or stream that carries it to a lake or ocean. -it can also be absorbed into the soil (groundwater) ~enters plants through their roots or flows into larger bodies of water or penetrates deeply enough into the ground to become part of underground reservoirs.

5. Nurtrient Cycles -nutrients-chemical substances that an organism needs to sustain life ~every organism needs nutrients to build tissues & carry out life functions.

6. The Nitrogen Cycle -all organisms need nitrogen to make amino acids (used to build proteins & nucleic acid) which combine to form DNA & RNA -Nitrogen gas makes up 78% of Earth's atmosphere -Nitrogen fixation-process where bacteria converts nitrogen gas into ammonia.