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Section 13-5 “Cycles” 13.5 Cycling of Matter KEY CONCEPT: Matter cycles in and out of an ecosystem. Fill in details as we go through the notes 13.5 Cycling of Matter The hydrologic cycle, or water cycle, is the circular pathway of water on Earth. precipitation condensation transpiration evaporation surface runoff lake groundwater water storage in ocean 13.5 Cycling of Matter Key terms for the water cycle: • Precipitation: moisture that falls to the ground (rain, snow, sleet, hail) • Evaporation: changing from liquid to gas (water to water vapor) • Transpiration: plants give off water vapor from their leaves to the air • Condensation: changing from gas to a liquid (little water droplets form on the outside of a cold glass of lemonade - that’s condensation) 13.5 Cycling of Matter • Oxygen Cycle: • Plants make food by photosynthesis –They use carbon dioxide (CO2) to make oxygen (O2) • Animals breathe out carbon by respiration –They use oxygen (O2) and breathe out carbon dioxide (CO2) –By the way … humans are animals too 13.5 Cycling of Matter Oxygen Cycle: oxygen photosynthesis respiration carbon dioxide 13.5 Cycling of Matter • Carbon is the building block of life. –The carbon cycle moves carbon from the atmosphere, through the food web, and returns to the atmosphere. –Carbon is also emitted by the burning of fossil fuels (like wood, oil, gasoline, and coal) 13.5 Cycling of Matter 13.5 Cycling of Matter The Nitrogen Cycle The nitrogen cycle mostly takes place underground. nitrogen in atmosphere animals plant nitrogen-fixing bacteria in decomposers roots ammonification nitrogen-fixing ammonium bacteria in soil nitrifying bacteria denitrifying bacteria nitrates nitrifying bacteria nitrites 13.5 Cycling of Matter The Nitrogen Cycle Nitrogen-fixing bacteria convert nitrogen gas in the atmosphere into ammonia. Ammonification: Decomposers break down animal excretions, dead animal and plant matter and convert nitrogen into ammonium. Nitrifying bacteria change the ammonium into nitrate. Denitrifying bacteria use nitrates as an oxygen source and release nitrogen gas into the atmosphere. 13.5 Cycling of Matter The Nitrogen Cycle Some nitrogen fixing bacteria live in nodules on roots of plants such as beans and peas; others live freely in soil. nitrogen in atmosphere animals plant nitrogen-fixing bacteria in decomposers roots ammonification nitrogen-fixing ammonium bacteria in soil nitrifying bacteria denitrifying bacteria nitrates nitrifying bacteria nitrites 13.5 Cycling of Matter – Nitrogen moves through the food web and returns to the soil during decomposition. nitrogen in atmosphere animals plant nitrogen-fixing bacteria in decomposers roots ammonification nitrogen-fixing ammonium bacteria in soil nitrifying bacteria denitrifying bacteria nitrates nitrifying bacteria nitrites 13.5 Cycling of Matter 13.5 Cycling of Matter The Phosphorus Cycle • Begins when phosphate is released by the weathering of rocks. • Phosphorus moves from producers to consumers through the food web. • Decomposers break down dead organisms which release phosphorus back into the soil or water for producers to use. • Some phosphorus leaches into groundwater from the soil and settles at bottom of bodies of water such as lakes; over thousands of years the phosphorus in the sediments eventually become rock again, and the cycle continues. 13.5 Cycling of Matter Both mining and agriculture runoff also add phosphorus into the environment.