Metabolism is the sum of chemical reactions taking place in the living organisms. Cellular respiration is one such metabolic process. Cellular respiration takes place in in the all organisms in which respiratory substrate such as glucose is oxidised completely in presence of oxygen to produce carbon dioxide, water and energy (ATP). Cellular respiration begins in cytoplasm and completes in the mitochondria of the cell. The energy is used to do work.
The simplest definition of an ecosystem is that it is a community or group of living organisms that live in and interact with each other in a specific environment.
