Final answer:
Mitochondria and chloroplasts evolved through endosymbiotic events, where ancestral cells engulfed bacteria. The evidence for these origins includes similarities in size and features between mitochondria, chloroplasts, and bacteria, as well as the presence of their own DNA and ribosomes.
Step-by-step explanation:
The evolution of mitochondria and chloroplasts is believed to have occurred through endosymbiotic events. In this process, ancestral cells engulfed aerobic bacteria (leading to the evolution of mitochondria) and photosynthetic bacteria (leading to the evolution of chloroplasts). The evidence for these origins includes similarities in size and features between mitochondria, chloroplasts, and bacteria, as well as the presence of their own DNA and ribosomes. These findings support the endosymbiotic theory proposed by Lynn Margulis in the 1960s.