What are some questions scientists still have about endosymbiosis?

One of the question is When was endosymbiosis made.
Endosymbiosis occured when a simple organism evolved into a much more complex organism.
After many researches, it is predicted that endosymbiosis started to happen ardound 1.5 billion years ago.

Corporate governance refers to the legal rules that structure, empower, and regulate the agents of organizations and define their relationships to the owners. 

Corporate governance is a set of rules by which a company is controlled by the government. They help balance the company, stakeholders, shareholders, management, customers, supplies, the community and much more. These corporate rules fully direct how a company works and what it is and is not allowed to do.