What is a major distinction between multicellular and unicellular organisms?

Multicellular organisms are characterized by their composition of multiple cells that can differentiate into various types, each adapted to perform specific functions essential for the organism's survival. This specialization allows multicellular organisms to develop complex structures, such as tissues and organs, where different cell types work together to carry out various tasks. For example, in humans, muscle cells facilitate movement, nerve cells transmit signals, and blood cells transport oxygen.

In contrast, unicellular organisms consist of a single cell that must perform all necessary life processes within that one cell. While they can exhibit a range of metabolic activities, they do not have the complex organizational structure that allows for job specialization seen in multicellular organisms. Thus, the ability of multicellular organisms to have specific functions assigned to different cell types is a significant distinction from unicellular organisms.