History of the p'hood
The sons of Moses and of Aaron and the seed of Abraham. D&C 84:34 (Hint: think of the answer in question form)
Serve as special witnesses of Jesus Christ to all the world, Build up and regulate the affairs of the Church, Holds the keys of the kingdom of God on the Earth, is a prophet seer, and revelator. D&C 23,33
What are the duties of an Apostle?
Fulfills the responsibilities of elder and high priest, and gives guidance as a mouthpiece of god, through blessings. (Hint: received ages 14-18 typically)
What are the duties of a Patriarch?