Why cell is called the structural and functional unit of life?

The cells are called as structural and functional units of a living body. Cells are structural unit as they form the structure of the organism. Cells combine to form tissues, which further combine to form organs, organs combine to form organic systems, which further combine to form organism. So, cell is the basic structural unit for all unicellular and multi-cellular organisms.

Cells can take in energy and use it and respond to their environment and maintain organization of loose materials inside the cell. Some of the basic ‘life processes’ or functions’ takes place in every cell to keep the organisms alive such as digestion, respiration, excretion, etc., whether it is a single-celled organism or multi-cellular organism. So, the cells are also called the functional unit of life owing to these processes.

EXPLANATION: Cell contain nucleus which has hereditary material of life called DNA. Because of this cell is called the basic unit of life. That’s because DNA (which gathers all the information needed to be a living being) cannot reproduce by itself and reproduction is a mandatory characteristic of any life on the planet.

Cells depend on pre-existing cells to exist, but that’s because they need something to pass them the information and new cells are generated through cell division (one cell upon division gives rise to two new cells (daughter cells)). Hence, cells can exist as a unit and the cell level is the first one (smallest one in scale) that can reproduce and transmit information in the form of DNA.

Since tissues, organs, organisms, are made up of cell complexes, it is said that the cell is the basic unit of life (it is present in every tissue or other living things from the cell level to all above).