The decomposition of organic molecule causes release of energy.
The process of decomposition simply refers to the process of disintegration of the molecules.
The biological activity causes the decomposition of many molecules. The decomposition of the organic molecule causes the breaking of bond, which release energy.
The organic decomposition can take place inside, as well as outside the body of an organism. The energy released by decomposition of molecules inside the body of an organism helps in carrying out processes required for survival.