1. Biogeochemical Cycles
SB4b. Explain the flow of matter and energy through ecosystems by explaining the need for cycling of major nutrients (C, O, H, N, P).

2. How are substances recycled through the ecosystem?
Chemicals oscillate between biotic organisms & abiotic reservoirs
Abiotic reservoirs- where chemical is “stockpiled” outside organism.
Ex: air, water, soil

3. Why is NITROGEN important to your survival?
Nitrogen- from proteins you eat, broken down by body to build new proteins & enzymes, repair cells

5. NITROGEN CYCLE Even though 78% of atmosphere is nitrogen, can’t get nitrogen by breathing in air. Your blood has no ability to remove nitrogen from air you inhale so you have to eat food with nitrogen in it.
Lightning can bond with nitrogen gas in the air and add solid nitrogen to soil.
Nitrogen fixing bacteria on roots of legumes (clover) take nitrogen gas out of the air and turn it into usable form for plants.
Plants store nitrogen in their body tissues
Animals eat plants and obtain nitrogen. Nitrogen is used to make proteins throughout body.
Plants & animals defecate or die and bacteria return nitrogen to the soil.
Other bacteria in soil return nitrogen to the air.

6. How are humans altering the nitrogen cycle?
Chemical fertilizers from farms or feces from feedlots overload nitrogen in soil or water
causes algae to grow
algae overpopulate, compete, & die
algae decompose
Decomposers use up oxygen in water
fish die
This process is called EUTROPHICATION.

7. Why is CARBON & OXYGEN important to your survival?
Carbon & Oxygen- from C6H12O6 (glucose) used as energy source in body. Oxygen inhaled & used to break down C6H12O6

9. CARBON/OXYGEN CYCLE
Plants and algae convert carbon dioxide (CO2) from the air or water into organic compounds (C6H12O6 - which is food) during photosynthesis. Oxygen is also released.
Animals eat plants and get the carbon from C6H12O6 into their bodies. This carbon provides the body with energy. Oxygen from plants is also inhaled by animal & used to break down C6H12O6.
Carbon is returned to the air or water when animals & decomposers exhale CO2.
Carbon is returned to soil when decomposers break down feces and dead bodies.

10. How are humans altering the Carbon/Oxygen Cycle?
burning EXCESS fossil fuels= more CO2 in air.
cutting down trees= less CO2 removed from air.
More heat is retained= Global warming

11. Why is HYDROGEN & OXYGEN important to your survival?
Hydrogen & Oxygen- from H2O (water) used in chemical reactions in body.

13. WATER CYCLE Water enters the atmosphere via a. Evaporation
b. Transpiration thru plants (plants giving off water as by-product of photosynthesis)
c. Cellular Respiration- water is given off as a by-product of breaking down food to store energy.
Condensation- water cools and forms clouds
Precipitation- clouds build and release liquid in form of rain, snow, sleet, or hail.
Run Off- Water rolls off land into a body of surface water (lake, pond, stream)
Infiltration- Water percolates thru soil and recharges/refills aquifer

14. How are humans altering the water cycle?
Cutting down trees, decreases transpiration, may change rainfall patterns
Septic tanks store waste water for some homes instead of sewer pipes. Water stored in septic tank is not immediately returned to river.

15. Why is PHOSPHORUS important to your survival?
Phosphorus- from foods you eat, used to make ATP (energy storage molecule)

16. PHOSPHOROUS CYCLE Phosphorus (P) stored in rocks
Weathering of rocks adds P to soil.
Plants take up P thru roots
Animals eat plants
Decomposers return P to soil.
Cycle starts #3.

17. How are humans altering the phosphorus cycle?
Overflowing sewers can increase P levels which leads to death of water ecosystem
2. Cheaper detergents may contain phosphorus, if leakage occurs, eutrophication can occur (see nitrogen cycle)