Cycles

Energy and matter move through the biosphere very differently — energy flows one-way while matter is recycled throughout and between ecosystems. Matter can cycle through the biosphere because biological systems DO NOT use matter but recycle it. The matter can be assembled into living tissue or passed out of the body as waste products. Cycles

Cycles within Ecosystems Almost everything within an ecosystem is recycled. Water, carbon, nitrogen & phosphorus pass from the nonliving environment to living organisms & then back to the environment.

Water Cycle Water is the most important, non-living component of the ecosystem. Nonliving cycle: involves condensation, precipitation, & evaporation. Living cycle: involves plants in a process called transpiration.

Carbon is a major component of living tissue Carbon is a major component of living tissue. Carbon is recycled by organisms in the environment through the processes of photosynthesis, cellular respiration and decomposition of dead organic matter. Carbon is removed from molecules of CO2 gas and fixed into food molecules during the process of photosynthesis. Carbon is returned to the gas form when it is released during the process of respiration as CO2. The combustion (burning) of fossil fuels for energy and burning of forests for open land releases large amounts of carbon in the form of CO2..

About 80% of the atmosphere is made up of nitrogen gas About 80% of the atmosphere is made up of nitrogen gas. This large amount of nitrogen is only useable by certain species of bacteria found in the roots of plants that are able to convert nitrogen gas into a solid form of nitrogen called ammonia by a process known as nitrogen fixation Other bacteria in the soil convert ammonia into another form of nitrogen compounds called nitrates by a process called nitrification Plants will use the nitrates in the soil to make proteins. Animals eat plants and use the proteins in plants to make their own proteins. When these plants and animals die, decomposers will return the nitrogen in their bodies back to the soil. Another group of bacteria can bring some of the nitrates in the soil back into the atmospheric form of nitrogen gas in a process called denitrification. This then completes the cycle. Humans also add millions of tons of synthetic nitrates and phosphates to the soil every year as a form of fertilizer to grow plants.