Discuss the relationship between power and leadership

Discuss the relationship between power and leadership by answering the following questions in a minimum of 175 words:
What power must a leader have to lead effectively?
How can a leader acquire that power?
What mechanisms can be put in place to prevent the leader from abusing his or her power?
Support your responses with an example of a leader in a specific situation, real or imagined, such as the leader of a project team, the head of the marketing department, the CEO of a company, etc.