Download Notes: Biogeochemical Cycles

Biogeochemical Cycles Notes
Biogeochemical cycles move matter from the abiotic components to the biotic components
of an ecosystem.

THE WATER CYCLE – the continuous movement of water through Earth, its atmosphere,
and living things in an ecosystem.
 Three
1.
2.
3.
states of water:
Solid: snow, hail
Liquid: rain, mist
Gas: water vapor
A. Precipitation: rain or snow falling to Earth
- Seeps into the ground, falls in lakes, creeks, streams, and the ocean
B. Evaporation: water entering the atmosphere as vapor when it heats up.
C. Transpiration: water vapor leaving plants to enter the atmosphere.
D. Respiration: when producers and consumers release water vapor to the atmosphere when
converting glucose to ATP in their mitochondria.
E. Condensation: when water vapor condenses back to liquid water as precipitation.

THE CARBON CYCLE – PS and CR drive the cycle of carbon through an ecosystem.
- Remember,…all the macromolecules that are needed by our cells contain carbon. All
organic!
 Three states of carbon:
1. Solid: fossil fuels, coal & oil
2. Liquid: as bicarbonate (CH3O+)
3. Gas: carbon dioxide (CO2) in the atmosphere
A. Producers make C6H12O6 [glucose]; consumers eat producers and other consumers to get
carbon based molecules (carbs, lipids, protein, nucleic acids)
B. Plants and animals release carbon into the atmosphere as CO2 through CR.
C. Decomposers also release carbon into the atm.as CO2 when they break down organic
matter.
D. Plants remove CO2 from (B. & C.) the atmosphere when they go through the process of
carbon fixation during the light independent reactions of PS.
- Use energy from ATP to rip apart CO2 and attach the carbon to the pre-cursor to
glucose.
Note:


Plants release oxygen when they go through PS.
Both plants and animal require oxygen to go through aerobic respiration.

THE NITROGEN CYCLE
- All organisms need to make proteins and nucleic acids, both which contain nitrogen.
- Nitrogen gas (N2) = 80% of the atmosphere.
A. Nitrifying bacteria that live on the roots of plant and in the soil, “fix” the nitrogen into
a form called nitrate
B. Plants use the nitrate to make amino acids.
- Plants don’t eat protein to get the a.a monomers they need to make their own
protein, so they have to get these a.a. another way…
C. Consumers (herbivores & omnivores) eat plants and use the nitrates in plants to make
protein and DNA.
D. Decomposers break down dead plants and animals to release nitrogen back to the soil.
E. Denitrifying bacteria finally turn the nitrogen in the soil back into nitrogen gas (N2) and
return it to the atmosphere.