1. CYCLING IN THE ECOSYSTEM
18.4 pp

2. DEFINITIONS
Ecosystem: an environment where the living (biotic) and non-living (abiotic) things affect one another
Biogeochemical process: circulation of substances through living organisms and the environment

3. 1. WATER CYCLE

4. 1. WATER CYCLE
Evaporation: water vapor enters the atmosphere

5. 1. WATER CYCLE Evaporation: water vapor enters the atmosphere
Transpiration: evaporation of water through the leaves of plants

6. 1. WATER CYCLE
Precipitation: water vapor that leaves the atmosphere (rain and snow)

7. 2. Oxygen Cycle
Plants release O2 as a waste product during photosynthesis
oxygen
respiration
carbon
dioxide
photosynthesis

8. 2. Oxygen Cycle
Plants release O2 as a waste product during photosynthesis
Humans and other organisms take in O2 and release it as CO2
oxygen
respiration
carbon
dioxide
photosynthesis

9. 3. CARBON CYCLE

10. 3. CARBON CYCLE
Photosynthesis: converting light energy into organic compounds (C6H12O6)

11. 3. CARBON CYCLE
Cellular respiration: breaking down organic compounds to release energy
(C6H12O6  CO2 + H2O + ATP)

12. 3. CARBON CYCLE
Combustion: burning of fossil fuels for energy releases CO2

13. 4. NITROGEN CYCLE
70% of atmosphere is nitrogen, but it is not in a ready to use form
N2 needs to converted into NH3 (ammonia)

14. 4. NITROGEN CYCLE Bacteria and decomposers play major role.
Takes place mostly below ground.

15. 4. NITROGEN CYCLE Plant takes in N from soil
Herbivore eats plant and gets N
Organism dies and N is released by bacteria and decomposer in soil for Plant