Section 3 Cycling of Materials in Ecosystems Grade 10 Biology Spring 2011

 Summarize the role of plants in the water cycle  Analyze the flow of energy through the carbon cycle  Identify the role of bacteria in the nitrogen cycle

 Biogeochemical cycle:  Pathway forms when a substance enters living organisms, such as trees, from the atmosphere, water, or soil  Stays for a time in the organism  Then returns to the nonliving environment

 Water has greatest influence on the ecosystem’s inhabitants

 Nonliving Portion: water vapor in atmosphere condenses and falls to earth’s surface  Becomes part of:  Groundwater: water retained beneath the earth’s surface  Some left on earth’s surface reenters atmosphere by evaporation

 Living Portion:  Water taken up by roots of plants  Transpiration: water evaporation from plant leaves

 Carbon dioxide in the air or dissolved in water is used by photosynthesizing plants, algae, and bacteria as a raw material to build organic molecules

 Carbon atoms can return to carbon dioxide in atmosphere or water in 3 ways: 1. Respiration: byproduct of cellular respiration 2. Combustion: burning of fuels (wood, fossil fuel) 3. Erosion: carbon in limestone (from shells of dead organisms) erodes and releases carbon

 Phosphorous essential part of proteins, nucleic acids, ATP  Usually present in soil and rock as calcium phosphate, which dissolves in water to form phosphate ions  This can be absorbed by roots of plants and used to build organic molecules  Animals that eat the plants reuse organic phosphorous

 Atmosphere = 78% nitrogen gas  Most organisms are unable to use nitrogen in this form  Some bacteria are capable of “fixing” nitrogen to a usable compound (ammonia)  Live in soil, associate with roots of legumes (nodules)  Nitrogen Fixation: process of combining nitrogen with hydrogen to form ammonia (NH 3 )

 Four stages of nitrogen cycle: 1. Assimilation: absorption and incorporation of nitrogen into organic compounds by plants 2. Ammonificatin: production of ammonia by bacteria during the decay of organic matter 3. Nitrification: production of nitrate from ammonia 4. Denitrificatin: conversion of nitrate to nitrogen gas

 Create Cycle Books for each of the cycles in this section  Water cycle:  Precipitation, transpiration, runoff, evaporation, water vapor, ground water  Carbon Cycle:  Carbon dioxide in atmosphere, CO2 in water, cellular respiration, photosynthesis, combustion, death and decomposition, lime stone, fossil fuels, erosion

 Nitrogen Cycle:  Atmospheric nitrogen gas, nitrogen fixation, nitrogen fixing bacteria, decomposers, ammonification, nitrification, nitrifying bacteria, assimilation, denitrification  Bonus: Phosphorous Cycle:  Rain, phosphate mining, fertilizer, runoff, phosphate in water, decomposition, phosphate in soil, phosphate in rocks