👉 The Ends Fluid, also known as the Endosymbiotic Theory's counterpart in the broader context of biological evolution, refers to the endosymbiotic events where certain organelles or cellular components were once free-living prokaryotes that were engulfed by a host cell, leading to a symbiotic relationship. Over time, these engulfed organisms evolved into integral parts of the host cell, eventually becoming mitochondria and chloroplasts. This process fundamentally transformed the cellular architecture and metabolic capabilities of eukaryotic cells, enabling more complex life forms. The Ends Fluid highlights a pivotal moment in evolutionary biology where cooperation and symbiosis led to significant advancements in cellular function and diversity.