The Four Kingdoms

The four kingdoms in biology classify all living organisms based on shared features: Bacteria (unicellular, no nucleus, simple cell structure), Archaea (similar to bacteria but with distinct biochemistry, often in extreme environments), Protista (mainly single-celled or simple multicellular organisms like algae), and Fungi (organisms like mushrooms and molds that absorb nutrients from their environment). These groups help scientists organize the diversity of life, understand evolutionary relationships, and study organism functions more effectively.