What does the endosymbiotic theory explain?

The endosymbiotic theory explains the development of eukaryotes, which are complex cells with membrane-bound organelles, including a nucleus. This theory posits that eukaryotic cells originated through a symbiotic relationship between different species of prokaryotes. According to this theory, early ancestral eukaryotic cells engulfed certain prokaryotic organisms, such as mitochondria and chloroplasts, which then became integral parts of the host cell. Over time, these engulfed organisms lost their independence and evolved into the organelles we see in eukaryotic cells today. This process allowed for greater cellular complexity and specialization, marking a significant step in the evolution of life on Earth, leading to the diverse array of eukaryotic organisms we have today, including plants, animals, fungi, and protists.

Other options refer to subjects that are not related to the endosymbiotic theory. Prokaryotes, while foundational to the development of life, are not explained by this theory. The origin of viruses is a different topic, often dealing with how they evolved separately from cellular life, and the evolution of bacteria does not pertain to the development of eukaryotic cells as described by the endos