Multicellular organisms have specialized cells that perform different kinds of tasks. All these specialized cells depend on each other and work together as a system.

The level of organization in a multicellular organism, which are arranged from simple (1) to complex (5), are listed below:

1. individual cells
2. tissues
3. organs
4. organ systems
5. organism

The level of organization in a multicellular organism starts with the individual cells. These individual cells make up a tissue, and tissues make up an organ. When organs with similar functions are grouped together, they form an organ system, and in turn, these organ systems make up an organism.

All organisms are made up of cells and they follow the principles of basic chemistry. Both unicellular and multicellular organisms have genetic materials embedded in them and they even contain similar organelles. In terms of their activities, both unicellular and multicellular organisms grow, develop, reproduce, transform energy, and respond to stimuli.

Since muscle tissues require a lot of energy in order to move and perform its other functions, muscle cells contain a lot of mitochondria. Mitochondria are the organelles that function as the powerhouse of the cell. They produce energy in the form of ATP in which the cells can use in order to do its work.