Cells are the building blocks of life — yet the story of how complex eukaryotic cells arose from simpler prokaryotes is one of the most fascinating in biology. According to the Endosymbiotic Theory, certain key organelles (specifically mitochondria and chloroplasts) were once free‐living prokaryotes that were engulfed by ancestral host cells and eventually became permanent residents, helping their host become more complex. In this webquest you will: watch a video to understand the basic concep