The body of organisms is made up of cells. In multicellular organisms, these cells are arranged in different levels of complexity.
The simplest level of organization in living cells is the cell that if grouped to form a tissue which in turn forms an organ. Organs group to form a system that gives rise to the organism.
The ultimate source of energy is the sun. Another source is catabolism, while anabolism uses up energy.
Different forms of energy exists and they are continuously being converted from one form to another.
These include heat, mechanical, chemical, electrical, light and sound.
The science which deals with energy transformation from one form to another is called thermodynamics.
The laws of thermodynamics can be applied to life process.