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Ecology Unit Nutrient Cycles • Nutrient Cycles • The most common elements in biological molecules: Carbon, Nitrogen, Hydrogen, Oxygen, Sulfur, Phosphorus • These elements cycle through the biosphere, hydrosphere, geosphere and atmosphere. Nutrient Cycles All Nutrient Cycles include 3 key steps: •Producers take up chemicals from the nonliving environment (soil, water, air) and create organic compounds •Consumers feed on producers and use the chemicals for energy or structures. Some of the chemicals return to the environment as waste products. •Dead organisms are broken down by decomposers, returning chemicals to the soil, water and air in inorganic forms. Carbon Cycle • Why is Carbon important? • • • • All organic compounds (proteins, carbohydrates, nucleic acids, and lipids) contain carbon. 1 in every 10 atoms in a human body is carbon Forms structures Provides energy Carbon Cycle • The Carbon Cycle • • • • • • • • Carbon is “fixed’ by producers - producers absorb CO2 from the atmosphere during photosynthesis to produce glucose. Consumers take up carbon by eating plants Carbon returns to atmosphere through cellular respiration Carbon enters soil from animal waste and decomposition Carbon in the soil can be converted to fossil fuels Carbon can also be absorbed by the oceans Burning fossil fuels returns CO2 to the atmosphere Carbon-rich rocks, like limestone, release carbon to the atmosphere through weathering. Carbon Cycle Water Cycle • The Water Cycle • • • • • Solar energy evaporates water from land and ocean, adding water vapor to the atmosphere The water cools and condenses, forming precipitation. Plants absorb water from soil Consumers take up water directly or from plants they consume Plants lose water to the atmosphere through transpiration • Most of the water cycle takes place between the atmosphere and the oceans in evaporation and precipitation. Water Cycle Nitrogen Cycle • The Nitrogen Cycle • • • • • • • N2 from the atmosphere is fixed by bacteria in the soil and in the roots of some plants to form ammonia (NH3) Bacteria also convert ammonium (NH4+) from the soil to form nitrates. This process is called nitrification. Producers absorb ammonia and nitrates from the soil and convert them to amino acids. Consumers obtain nitrogen from plants Ammonium returns to the soil from waste and decomposition Denitrifying bacteria convert some nitrates back to N2 and release to the atmosphere. Lightening can also create enough pressure and energy to convert N2 to ammonia (NH3) Nitrogen Cycle Little nitrogen is exchanged with atmosphere Fertilizer is a source of a significant amount of nitrogen