AP environmental science - natural biogeochemical cycles

kunubivi's version from 2017-09-20 19:48

Section 1

Question Answer
Steps to nitrogen cycle1. Nitrogen fixation. 2. Nitrification. 3. Assimilation. 4. Ammonification. 5. Denitrification
Nitrogen fixation (atmospheric)nitrogen oxidized at high temp. to make nitrite (NO2). Can combine w/ water to form nitric acid (H2NO3), deposited on earth through rainfall. Accounts for 10% of of nitrate entering cycle.
Nitrogen fixation (biological)done by bacteria which can convert N2 into ammonia (NH3) if energy source is present. Can get this energy by directly absorbing sunlight or by living in roots of plants (provide them with food). Accounts for 90% of fixed nitrogen in cycle.
NitrificationConversion in which ammonia oxidized into nitrate, nitrite. 2 groups of microorganisms involved: nitrosomonas, nitrobacter
Assimilationbiological use. animals assimilate nitrogen based compounds by eating plants and other organisms that consume plants. Nitrates form of nitrogen most commonly assimilated by plants thru their root hairs.
AmmonificationBacteria/fungi convert initial form of nitrogen (from dead plants/animals, feces) back into ammonia.
Denitrificationprocess thru which nitrates reduced to gaseous nitrogen. Used by faculative anaerobics. Gaseous nitrogen returns to atmosphere, cycle restarts.

Section 2

Question Answer
Steps to water cycle1. solar energy evaporates water from oceans, lakes, rivers, streams, soil, vegetation. 2. Condensation. 3. Precipitation. 4. Runoff. 5. Percolation (other water seeps down into aquifers, etc), cycle begins again ooo
Oceans97% 0f all water on Earth. source of 78% of global evaporation. No oceans, temp. on land would rise to 153 degrees C

Section 3

Question Answer
Carbonfundamental element in carbohydrates, fats, proteins, nucleic acids. Building block of life
Steps in carbon cycle1. plants remove CO2 from air. 2. when plants/animals die, become buried in the earth. 3. after millions of years, remains become coal, oil. 4. People mine for these fossil fuels. 5. Burn fossil fuels, send up CO2, greenhouse gases back into atmosphere, cycle begins again.
Carbon sinks1. plant matter. 2. terrestrial biosphere. 3. oceans. 4. sedimentary deposits

Section 4

Question Answer
Phosphorusessential for production of nucleotides, ATP, fats in cell membranes, bones, teeth, shells. Found in sedimentary rocks. Does not depend on bacteria.
Steps in the phosphorus cycle1. released from rocks thru weathering, infiltrates soil,water. 2. absorbed by plants. 3. animals consume the plants, in turn consumed by other animals. 4. animals die, return to soils/oceans thru decay.

Section 5

Question Answer
Sulfur Found in underground rocks, deep oceanic deposits
Steps to sulfur cycle1. released from weathering of rock, gases released from seafloor vents, volcanic eruptions in form of either hydrogen sulfide, sulfur dioxide. 2. sulfur dioxide convert to sulfur trioxide to tiny droplets of sulfuric acid. 3. sulfuric acid mixes w/ rain, falls to Earth as acid rain.