The Tree of Life

Adam and Eve are already alive, so why do they need a tree of life? They're living creatures. So if this tree is to bestow life, then what exactly are they receiving? And I think the answer to that is pretty clear at the end of Genesis chapter 3. This is after Adam and Eve have consumed the fruit of the tree of the knowledge of good and evil. God has pronounced his curse upon the serpent and he's spoken both to Adam and to Eve.