Describe the cellular level of organization
Multicellular organisms are made up of millions of cells. Cells are the building blocks of life. They are the basic structural and functional units from which life takes shape. Cells are the smallest living entities in a living organism. The cells perform functions necessary for the survival of the organism, such as respiration, digestion, excretion, protection from pathogens and so on. Each cell performs a specific function in the body. Therefore, cells specialising in one function are often grouped together in the body. This means that a particular function is carried out by a cluster of cells at a definite place in the body. In this way, different functions are performed by different groups of cells in an organism. This constitutes the organisation at cellular level or cellular level of organisation.