Study guide for Unit 2 chapter 5
Ecosystem level biology
1. Nitrification​ - the conversion by bacteria of ammonium ions first into nitrite ions and then
into nitrate ions
2. Denitrification​ - ​process where nitrate is reduced and ultimately produces molecular
nitrogen
3. Nitrogen fixation​ - the process by which inert nitrogen gas combines with hydrogen to
form ammonium ions which are chemically and biologically active and can be taken up
by plants
4. Assimilation​ - ​process by which plants and animals absorb the NO3- and ammonia
5. Ammonification ​- when the organism​ dies and is left to be converted back into
ammonium by decomposers and reenter the ​cycle.
6. Positive Feedback​ - a feedback loop in which output of one types acts as input that loves
the system in the same direction. The input and output drive the system ​further​ ​towards
one extreme of another.
Negative Feedback​ - a feedback loop in which output of one type acts as input that moves
the system in the opposite direction. The input and output ​essentially neutralize ​each
others effects, ​stabilizing​ the system.
7. Calculate NPP, given GPP and producer respiration
Gross Primary Productivity (GPP) - Respiration
8. ****Know the most productive and least productive biomes (there’s a shortcut to
knowing this!)
9. Why is Carbon an important element?
- ​carbon​ is one of the essential building blocks of organic life.
10. Know the 6 parts of the carbon cycle and what happens to carbon during each part:
a. Photosynthesis
Carbon + Water + Energy → Sugar + Oxygen
b. Respiration
Sugar + Oxygen → Carbon + Water + Energy
c. Burial and Lithification
C-RICH sediments and organic matter → rocks and fossil fuels
d. Mining
Move Carbon from underground to the surface
e. Combustion
Carbon + Oxygen → Carbon Dioxide
f. Weathering and Erosion
LIMESTONE
Calcium Carbonate (CaCO3) → Carbon Dioxide (CO2)
11. Know the largest reservoirs for each of the biogeochemical cycles
Nitrogen​ - Atmosphere
Water​ - Ocean
Carbon​ - Fossil Fuels, Soil, Organisms, Atmosphere
Phosphorus​ - Rocks
12. Know the 5 parts of the nitrogen cycle and what happens to nitrogen during each part:
A. Fixation
- Carried out by N-Fixing Bacteria free living in soil
- Mutualism - bacteria live in nodules (rhizomes) on roots of legumes
Nitrogen (N2) → ​Ammonia (NH3) + Ammonium (NH4)
B. Nitrification
- Carried out by soil bacteria
Ammonia (NH3) + Ammonium (NH4) → Nitrite (NO2-) → Nitrate (NO3-)
- Nitr​I​te - TOX​I​C
- Nitr​A​te - Pl​A​nts use
C. Assimilation
- Plants absorb…
- Ammonia (NH3)
- Ammonium (NH4)
- Nitrate (NO3-)
D. Ammonification
- Decomposer Bacteria
N-RICH Wastes → ​Ammonia (NH3) + Ammonium (NH4)
E. Denitrification
- Soil Bacteria
Nitrite (NO2-) → Nitrogen (N2) +Nitrous Oxide (N2O)
- Nitrous Oxide (N2O) - Greenhouse Gas
13. Know the processes in the water cycle:
A. Evaporation
B. Condensation
C. Precipitation
D. Infiltration
E. Transpiration
F. Runoff
G. Groundwater
14. What are the sources of excess phosphorus in the environment?
- Inorganic Fertilizer
- Detergents
- Animal Wastes
- Sewage
- Agriculture
15. What is Net Primary Productivity and How is it different from Gross Primary Productivity?
Net Primary Productivity​ - what’s left after producer respiration and what is available for
consumers.
Gross Primary Productivity​ - the total amount of chemical energy produced by autotrophs as
they convert sunlight into chemical energy during photosynthesis
16. Why are flex fuel vehicles potentially better for the environment than conventional gasoline
burning vehicles?
- Flex Fuel vehicles use fuel from crops like corn and sugarcane and releases CO2 that can
be absorbed by the crops
17. What’s cultural eutrophication, why does it happen, what are the steps in the process.
- Cultural Eutrophication​ - excess nitrogen in water
- Impacts​ - Destroyed Wetlands, Animal Waste, Deforestation
- Steps
1. excess nutrients enter waterways.
2. nutrients promote algae growth and algal bloom occurs.
3. algae die and are decomposed by bacteria, increasing biological oxygen demand
4. oxygen levels drop and aquatic life forms die.
- Solution -​
1. Reduce Use - Substitute or Change expectations
2. Timing of Application - use fertilizer when plants need it
3. Animal Waste Management - Control
4. Maintain Plants/Wetlands
18. What are the five steps in the phosphorus cycle?
A. Rock (PO4^-3)
B. Weathering and Erosion
C. Assimilation
D. Decomposers
E. Deposition
F. Burial Lithification