BIOL 226 Chapter Notes - Chapter 55: Primary Production, Chemosynthesis, Photic Zone
Document Summary
Ecosystem the sum of all the organisms living in a given area and the abiotic factors with which they interact. Ecosystem"s dynamics = energy flow and chemical cycling. Chemical elements, such as carbon and nitrogen, are cycled among abiotic and biotic components of the ecosystem. Photosynthetic and chemosynthetic organisms assimilate these elements in inorganic form from the air, soil, and water and incorporate them into their biomass, some of which is consumed by animals. The elements are returned in organic form to the environment by the metabolism of plants and animals and by organisms such as bacteria and fungi that break down organic wastes and dead organisms. An ecosystem must be powered by a continuous influx of energy from an external source in most cases, the sun. Energy cannot be created or destroyed but only transferred or transformed (1 st law of thermodynamics) Plants and other photosynthetic organisms convert solar energy to chemical energy.