What is unicelular?

Unicellular organisms are those organisms that are composed of a single cell and perform all their life activities within that cell. They are the simplest forms of life, and they include all bacteria and some protists, such as amoebas and paramecia. Unicellular organisms can reproduce asexually by dividing into two identical cells, or they can reproduce sexually by exchanging genetic material with another unicellular organism. They have a very simple structure, with no specialized organs or tissues, and they receive nutrients and eliminate waste through a process known as diffusion. Unicellular organisms play important roles in the ecosystems, such as breaking down organic matter and acting as a source of food for larger organisms.