Cycles (Water, Carbon, Nitrogen) Biological Cycles: repeating events that are needed for life to survive Water Cycle Carbon Nitrogen There are others important cycles as well that effect life Phosphorus cycle, nutrient cycle, rock cycle, weather cycles

Learning Objectives: Know all the basic steps of the Water, Carbon, & Nitrogen Cycles Recognize what drives the Water Cycle and where fresh water comes from Recognize what drives the Carbon Cycle and how it can be effected by human activities Recognize the “weak points” in the Carbon & Nitrogen Cycles

Pg 75 THE WATER CYCLE Solar energy Transport over land Cloud movement by wind Precipitation over land Precipitation over ocean Evaporation & transpiration from land Evaporation from ocean Percolation through soil Runoff and groundwater

Water Cycle (hydrologic cycle): All water moves in a global cycle (it keeps a steady, but small, supply of fresh water available for human use) powered by solar energy

Transpiration: loss of H20 by plant leaves as photosynthesis occurs (liquid vapor)

Evaporation: liquid H20  water vapor (needs sunlight to the heat water)

Where does most rainwater come from in the world?

Water Cycle allows freshwater supplies on earth to be refilled

Water Cycle allows freshwater supplies on earth to be refilled

Problems in the Water Cycle

Pg 75 THE WATER CYCLE Solar energy Transport over land Cloud movement by wind Precipitation over land Precipitation over ocean Evaporation & transpiration from land Evaporation from ocean Percolation through soil Runoff and groundwater

Pg 77 THE CARBON CYCLE CO2 in atmosphere Photosynthesis Cellular respiration Burning of fossil fuels and wood Higher-level consumers Primary consumers Carbon compounds in water Decomposition

Carbon Cycle: Reflects the reciprocal processes of photosynthesis and cellular respiration (metabolism) Autotrophs/Producers get the carbon they need to make their food (photosynthesis) and to grow bigger in size from CO2 in the air, NOT the soil (nutrients and water only) Heterotrophs/Consumers get the carbon they need to grow from their food, but also they release CO2 for respiration (cellular respiration)

Carbon Cycle: CO2 is a known greenhouse gas: (traps heat for sun) The burning of fossil fuels (oil/coal) adds more CO2 to the atmosphere (so it is thought more heat will get trapped) Note: the Greenhouse effect is a natural process that keeps the earth from cooling off too much Global warming is thought to be the result of adding to much CO2 into the atmosphere, greatly increasing the greenhouse effect

Pg 77 THE CARBON CYCLE CO2 in atmosphere Photosynthesis Cellular respiration Burning of fossil fuels and wood Higher-level consumers Primary consumers Carbon compounds in water Decomposition

Pg 78 End THE NITROGEN CYCLE N2 in atmosphere (use-less) Assimilation Nitrogen-fixing bacteria in root nodules of legumes Denitrifying bacteria NO3 Decomposers Nitrifying bacteria Nitrification Ammonification NH3 NH4+ NO2  Nitrogen-fixing soil bacteria Nitrifying bacteria End

The Nitrogen Cycle Nitrogen fixation - Only a few types of bacteria (that live in the roots of plants called Legumes) can make Useless N2 In the atmosphere Useful ammonia NH3 In the soil Legumes

Consumers get the Nitrogen they need from eating plants (or animals that eat plants) after plants absorb nitrogen from the soil/oceans Consumers return nitrogen to soil/oceans with wastes like urine (urea is a molecule with nitrogen) and when organisms bodies decay in the soil Nitrogen in the soil may be returned to the atmosphere after denitrification (another bacteria does this) Urea

Nitrogen based-molecules (like ammonia) are also used a lot in fertilizers to increase the size and growth rate of plants

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