1. Biogeochemical Cycles

2. Water
Cycle
Defined: Movement of water through the Earth and its atmosphere
75% of the Earth is covered in water
Less than 1% is drinkable.
Most water is salty or frozen

3. Water Cycle Pathway Water vapor starts to cool…condensation occurs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Water vapor starts to cool…condensation occurs
Condensation: process where water vapor turns into a liquid
Evaporation: Heat changes water from a liquid to a gas
Transpiration: Water evaporates from the leaves of plants through openings called stomata
Precipitation: Rain, snow, sleet, or hail falls when water drops become heavy
Runoff: Water runs down hill into rivers, lakes, streams, oceans…
Infiltration: Water soaks into the soil and collects as groundwater

7. Oxygen Cycle Autotrophs: Release O2 into atmosphere by photosynthesis
Most life needs O2 for cellular respiration
Creates ATP (energy) for cells

8. Carbon (C) Cycle Plants Decomposers Animals Human Contribution
glucose
glucose
glucose
CO2
glucose
glucose
glucose
Carbon
Human Contribution
Release excess CO2 into atmosphere when fossil fuels (coal, oil, natural gas) are burned for energy
Cycle is out of balance
Plants
Absorb CO2 for photosynthesis
Release glucose (C6H12O6) after photosynthesis
Decomposers
Obtain glucose by feeding on dead organisms
Carbon released in their waste
Animals
Glucose passed up the food chain
CO2 exhaled into atmosphere

9. Phosphorus (P) Cycle Phosphorus needed to make ATP, DNA, lipids
Problem: No phosphorus in atmosphere
Step 1: Phosphorus released by weathering of rocks
Step 2: Producers absorb P through their roots
Step 3: Consumers ingest P
Step 4: Decomposers obtain P when feed on the dead.
Step 5: Decomposers release P within waste back into soil or water
Cycle repeats P P P P P

10. Phosphorus (P) Cycle Human Contribution P P P P
Adding excess P from fertilizers
P washes into lakes, etc…
Excess P causes extreme plant & algae growth P P

11. Nitrogen (N) Cycle Nitrogen needed to build nucleic acids (DNA/RNA)
Step 4: Producers absorb N through their roots
Step 5: Consumers ingest N through the food chain
Step 6: Decomposers obtain N from dead organisms… return N to soil in their waste
Nitrogen needed to build nucleic acids (DNA/RNA)
Problem: Nitrogen in atmosphere (N2) is unusable
Step 1: Bacteria in soil convert N2 into usable forms
Step 2: Bacteria absorb usable N
Step 3: Bacteria release N waste into air N2 N N N N N
Usable N
Usable N
Nitrogen fixation

12. Nitrogen (N) Cycle How does lightning help? O2 O O N2 N N N N2 N O O
Energy breaks atmospheric nitrogen into Nitrogen oxide
Nitrogen oxide falls in rain to soil

13. Review Name and define the 6 stages of the water cycle.
How is oxygen released into the atmosphere?
In which cellular process is oxygen removed and used from the atmosphere?
What are the 4 major types of organic molecules?
In which cellular process is carbon dioxide released into the atmosphere?
How are humans disrupting the carbon cycle?
Which objects release phosphorus over time?
How are humans disrupting the phosphorus cycle?
Which organisms help convert gaseous nitrogen into a usable form of nitrogen in the nitrogen cycle?
How do plants obtain nitrogen?
Of the major molecules that we have studied this year, which ones contain nitrogen and/or phosphorous?