The ‘cell’ is the smallest structural unit of living matter that is capable of functioning independently. A single cell can be a complete organism in itself, as can be seen in bacteria and protozoans. A unicellular organism also captures and digests food, respires, excretes, grows and reproduces.
Similar functions in multi-cellular organisms are carried out by groups of specialized cells which are organized into tissues and organs such as the higher plants and animals. Hence, a ‘cell’ is known as the basic structural and functional unit of life.