RNR study guide chap 3 pt 2

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ndumas2
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36549
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RNR study guide chap 3 pt 2
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2010-09-22 04:58:23
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pt 2 of study guide
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  1. explain the Carbon cycle
    : cyclic movement of carbon in different chemical forms from the environment to organisms and then back to the environment
  2. Transformations of carbon as it moves through the biosphere
    Effects of human activities on the carbon cycle
  3. We clear trees and other plants that absorb CO2 through photosynthesis faster than they can grow back
  4. Some Human effects on the carbon cycle...
    • We add large amounts of CO2 by burning fossil fuels and wood
    • Greenhouse affect: helps warm the lower atmosphere and the earth’s surface. The resulting global warming could disrupt global food production and wildlife habitats, alter temperature and precipitation patterns, and raise the average sea level in various parts of the world.

    Caused/enhanced by increased concentrations of atmospheric CO2 and other gases
  5. Nitrogen cycle
    cyclic movement of nitrogen in different chemical forms from the environment to organisms and then back to the environment
  6. Nitrogen fixation
    conversion of atmospheric nitrogen gas into forms useful to plants by lightning, bacteria, and cyanobacteria; it is part of the nitrogen cycle
  7. Specialized bacteria in soil and aquatic environments convert (or fix) gaseous nitrogen (N2) to ammonia (NH3), which is converted to ammonium ions (NH4+) that can be used by plants
    Conversion of nitrogen gas to ammonia
  8. Explain Nitrification
    : ammonia not taken up by plants may undergo this process. It it’s a two step process where specialized bacteria convert most of the NH3 and NH4+ in soil first to nitrite ions (NO2-), which are toxic to plants, and then to nitrate ions (NO3-), which are easily taken up by the roots of plants. Animals in tern, get their nitrogen by eating plants or plant-eating animals
  9. Expain Wastes
    plants and animals return nitrogen-rich organic compounds to the environment as wastes, cast-off particles, and through their bodies when they die
  10. Ammonification
    vast armies of specialized decomposer bacteria convert this organic material into simpler nitrogen-containing inorganic compounds such as ammonia (NH3) and water-soluble salts containing ammonium ions (NH4+)
  11. Explain Dentrification
    nitrogen leaves the soil as specialized bacteria in waterlogged soil and in the bottom sediments of lakes, oceans, swamps, and bogs convert NH3 and NH4+ back into nitrite and nitrate ions, and then into nitrogen gas (N2) and nitrous oxide gas (N2O). these gases are released to the atmosphere to begin the nitrogen cycle again
  12. Effects of human activities on the nitrogen cycle
    • We add large amounts of nitric oxide into the atmosphere when N2 and O2 combine as we burn any fuel at high temperatures. In the atmosphere, this gas can be converted to nitrogen dioxide gas (NO2) and nitric acid (HNO3),which can return to the earth’s surface as damaging acid deposition, commonly called acid rain
    • We add nitrous oxide (N2O) to the atmosphere through the action of anaerobic bacteria on livestock wastes and commercial inorganic fertilizers applied to the soil. This gas can warm the atmosphere and deplete ozone in the stratosphere Nitrate (NO3-) ions in inorganic fertilizers can leach through the soil and contaminate groundwater, which is harmful to drink, especially for infants and small children
    • We release large quantities of nitrogen stored in soils and plants as gaseous compounds into the troposphere through destruction of forests, grasslands, and wetlands
    • We upset aquatic ecosystems by adding excess nitrates to bodies of water through agricultural runoff and discharges from municipal sewage systems
    • We remove nitrogen from topsoil when we harvest nitrogen-rich crops, irrigate crops (washing it out of the soil), and burn or clear grasslands and forests before planting crops
  13. Phosphorus Cycle
    cyclic movement of phosphorus in different chemical forms from the environment to organisms and then back to the environment
  14. Limiting factor to plant growth and it doesn’t cycle as quickly or readily as other elements because it is often stored in rive beds and the ocean for long periods of time
    • Effects of humans on phosphorus cycle
    • We mine large quantities of phosphate rock to make commercial inorganic fertilizers and some detergents
    • We reduce the available phosphate in tropical soils when we cut down areas of tropical forests
    • We disrupt aquatic systems with phosphates from runoff of animal wastes and fertilizers and discharges from sewage treatment systems
  15. Sulfur Cycle
  16. cyclic movement of sulfur in various chemical forms from the environment to organisms and then back to the environment
  17. Effects of humans on sulfur cycle
    • We burn sulfur-containing coal and oil to produce electric power
    • We refine sulfur-containing petroleum to make gasoline, heating oil, and other useful products
    • We convert sulfur-containing metallic mineral ores into free metals such as copper, lead, and zinc – an activity that releases large amounts of sulfur dioxide into the environment
  18. GAIA HYPOTHESIS
  19. Some have proposed that the earth’s various forms of life control or at least influence its chemical cycles and other earth-sustaining processes
    • The cycling of matter and the flow of energy through the biosphere and its ecosystems connects the earth’s past and current organisms. In this sense, the earth is an incredibly complex system that sustains itself and adapts to changing environmental conditions through an intricate network of positive and negative feedback loops.
    • Some people believe that the earth behaves like a single self-regulating system in which living things affect the environment in ways that make it possible for life to persist and flourish on the earth

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