Unicellular vs. Multicellular Organisms
Unicellular Organisms:
- Unicellular organisms consist of a single cell that performs all necessary functions for survival.
- They are typically microscopic and include bacteria, archaea, and protists.
- These organisms have a simple structure and rely on diffusion for nutrient intake and waste removal.
- Examples of unicellular organisms include amoeba, paramecium, and bacteria.
- They reproduce asexually through processes like binary fission or budding.
Multicellular Organisms:
- Multicellular organisms are composed of multiple cells that are specialized to perform specific functions.
- They range in size from microscopic organisms to large animals and plants.
- These organisms have complex structures with different types of cells organized into tissues, organs, and organ systems.
- Multicellular organisms exhibit division of labor, where cells specialize in different functions to ensure survival and growth.
- Examples of multicellular organisms include humans, animals, and plants.
- They reproduce sexually through processes like fertilization and meiosis.

Main Differences:
- Structure: Unicellular organisms are made up of a single cell, while multicellular organisms are composed of multiple cells.
- Size: Unicellular organisms are typically microscopic, whereas multicellular organisms can vary in size.
- Complexity: Multicellular organisms have complex structures with specialized cells, tissues, and organs, while unicellular organisms have a simpler structure.
- Reproduction: Unicellular organisms reproduce asexually, while multicellular organisms reproduce sexually.
- Function: Multicellular organisms exhibit division of labor among cells, whereas unicellular organisms rely on a single cell for all functions.