ECOLOGY

3. is the study of the relationships between living organisms their physical environment
5. the population of all species that occupy a habitat
9. CYCLE, the cycling of materials through living system and back to the earth
11. FACTORS, all environmental conditions required to support life
12. CHAIN, linear sequence of who eats whom in an ecosystem
14. FACTORS, living organisms in an ecosystem
15. organisms that ingest other organisms to obtain organic nutrients

1. LEVEL, all organisms that are the same number of energy transfer away from the original source of (e.g. sun light) that enters an ecosystem
2. reduction of nitrate or nitrite to gaseous nitrogen( N2) and a small amount of nitrous oxide (NO2) by soil bacteria
4. WEB, networks of many interlocked fiid chaunbs
6. a process by which certain soil bacteria strip ammonia or ammonium of electrons and nitrite (NO2) is released as a reaction product
7. heterotrophic bacteria and fungi that obtain organic nutrients by breaking down the remains of products of organisms
8. the total dry mass of all living organisms at a given tropic level of an ecosystem
10. community and its physical and chemical environment
13. FIXATION, assimilation of gaseous nitrogen (N2) from the air