Need for Energy in Living Organisms

All living cells carry out numerous activities e.g, they generally assemble macromolecules of all types, from raw materials, waste products are produced and excreted, genetic instructions flow from the nucleus to cytoplasm, vesicles are moved from Golgi bodies to the plasma membrane, ions are pumped across the membranes etc. For these high level of activities, a cell needs energy. The energy is used as fuel for life which is derived from light energy trapped by plant cells and converted into energy rich compounds. Other organisms, which do not have the ability to trap light energy, obtain their energy by eating plants or by eating the organism that eat plants. Capturing and conversion of this energy from one form to another in the living system and its utilization in metabolic activities is called bio-energetics.