Answer:
Secondary endosymbiosis is when a living cell engulfs another eukaryote cell that has already undergone primary endosymbiosis. It has happened often enough that it has led to genetic diversity among the organisms on Earth.
Explanation:
Examples are nitrogen-fixing bacteria (called rhizobia), which live in the root nodules of legumes; single-cell algae inside reef-building corals, and bacterial endosymbionts that provide essential nutrients to
