Betsy Sanford Lost Mountain Middle School 7th Grade Life Science Ecology - Cycles Betsy Sanford Lost Mountain Middle School 7th Grade Life Science

The Water Cycle What – the recurring flow of water throughout the atmosphere and the biosphere Who - all living things need water all forms of water, solid (snow, sleet, hail), liquid water & gas (water vapor) Where – throughout the biosphere and atmosphere When – constantly cycling Why – recycling of water for reuse in chemical reactions in living things How - changes in temperature cause evaporation, condensation, and precipitation precipitation collects above ground in lakes, ponds and ice flows precipitation runs off above ground into rivers, streams and oceans precipitation collects below ground in aquifer

The Nitrogen Cycle What – the recurring flow of nitrogen throughout the atmosphere and the biosphere Who – all organisms need nitrogen, but not in gas form (the atmosphere is 78% nitrogen) Where – needed in the soil wherever plants are growing When – constantly cycling Why – recycling of nitrogen for reuse in making proteins and DNA How – nitrogen gas must be chemically changed into forms plants can use to grow bacteria in the soil “fix” nitrogen (nitrogen fixation) plants take nitrogen from the soil and consumers eat plants to get nitrogen consumers die off and decomposers release nitrogen back into the soil lighting can “fix” nitrogen also

The Carbon Cycle What – the exchange of carbon back and forth from the environment to living things Who – all living things are made of carbon; carbon is part of the ocean, the air and even rocks Where – in the atmosphere as carbon dioxide (CO2) and in molecules such as glucose (C6H12O6) When – constantly cycling Why – plants use carbon dioxide to make food and all consumers use food for energy carbon dioxide is one of the greenhouse gases that blankets the Earth to keep it warm without this blanket of gases, the Earth would be totally frozen How – chemical reactions photosynthesis and cellular respiration when plants die and are buried for millions of years they become fossil fuels like coal and oil burning fossil fuels releases carbon dioxide into the atmosphere