TAMMY - What do you mean when you say that Adam's transgression was planned to happen, to open the way for the experiences of mortality? Does this mean that Mormons believe in predestination?

JOEL - Mormon's do not believe in predestination, but we do believe in something called foreordination. In predestination one has no choice in what he will do in life; it is set in stone and he can not change it. We believe that in our pre-earth life as spirit children of God certain individual were selected to come forth in mortality at specified times, under certain conditions, and to fulfill predesignated responsibilities.
But unlike predestination, foreordination does not preclude the exercise of agency. Many may be foreordained to high missions in mortality, but may, through sin and rebellion, fail in their foreordinations and give up their blessings.
Foreordination is a conditional preappointment to or bestowal of certain blessings and responsibilities. Of course no one can really know what they were foreordained to do, but as long as one remains faithful to God he can fulfill whatever mission he was preappointed to do. For example Jeremiah was foreordained to become a prophet.
The Lord said to him:
"Before I formed thee in the belly I knew thee; and before thou camest forth out of the womb I sanctified thee, and I ordained thee a prophet unto the nations" (Jer. 1:5).

Adam was foreordained to be placed on earth and bring about the fall, which made it possible for mankind to come to earth and work out his salvation. Because of the agency that God gave him, Adam made the choice to partake of the forbidden fruit. He could just as easily have chosen not to partake. I believe that's why God gave to Adam a wife, Eve, just to make sure he would do the right thing :-)