1. Biogeochemical Cycles
Biology EOCT Review

2. Essentials for Life
Like energy, matter flows through the environment. UNLIKE energy, which flows in one direction, matter cycles through the environment.
Matter is recycled in ecosystems through feeding relationships and life processes of organisms.
Essential elements: carbon (C ), oxygen (O), hydrogen (H), nitrogen (N), and phosphorus (P). When they cycle through organisms and environments it is called a biogeochemical cycle.

3. The Water Cycle

4. The Water (H2O) Cycle
Evaporation: water vapor enters the atmosphere as the sun heats bodies of water on the Earth’s surface
Transpiration: water evaporations from the leaves of plants through the stomata
Condensation: water vapor in the air and changes into a liquid
Precipitation: water that falls back to the Earth in the form of rain, hail, snow, or sleet

5. The Carbon Cycle

6. The Carbon Cycle
Organisms release carbon dioxide into the air as a waste product of cellular respiration.
Plants use carbon dioxide from the air in photosynthesis.
Coal and oil are fossil fuels formed from the remains of plants and other organisms. The burning of these fossil fuels releases carbon that was stored in the original organisms.
Carbon stored in the tissues of dead organisms is returned to the environment by decomposition.

7. The Nitrogen Cycle

8. The Nitrogen Cycle
Except for bacteria, living things cannot use N2 directly. Bacteria take nitrogen from the air and combine it with hydrogen to form ammonia (NH3)- nitrogen fixation.
Other bacteria transform ammonia into nitrates and nitrites- nitrification.
Denitrification is when bacteria convert the nitrates and ammonium ions in the soil back into nitrogen gas.

9. The Phosphorus Cycle

10. The Phosphorus Cycle
Only biochemical cycle that does not cycle through the atmosphere.
Phosphorus cycle is very slow.
Phosphorus is found in water, soil, and rocks.
Geological processes (hurricanes, tsunamis, earthquakes) release phosphorus from rocks and carry it from ocean sediment to land.
Plants absorb phosphorus.
Herbivores consume plants.
Phosphorus from decaying plants or animals returns to the earth.