cursed fig tree

i'm curious... what was the significance of Jesus cursing the fig tree in the book of Mark (11:12-14)?
12The next day as they were leaving Bethany, Jesus was hungry. 13Seeing in the distance a fig tree in leaf, he went to find out if it had any fruit. When he reached it, he found nothing but leaves, because it was not the season for figs. 14Then he said to the tree, "May no one ever eat fruit from you again." And his disciples heard him say it.
what was the significance? why would God curse a tree for doing what it was made to do? why would God be angry at it for not being in season? didn't he create it this way? or is it sin that makes it bloom every so often and not constantly?
later on it says:
20In the morning, as they went along, they saw the fig tree withered from the roots. 21Peter remembered and said to Jesus, "Rabbi, look! The fig tree you cursed has withered!"
22"Have faith in God," Jesus answered. 23"I tell you the truth, if anyone says to this mountain, 'Go, throw yourself into the sea,' and does not doubt in his heart but believes that what he says will happen, it will be done for him. 24Therefore I tell you, whatever you ask for in prayer, believe that you have received it, and it will be yours. 25And when you stand praying, if you hold anything against anyone, forgive him, so that your Father in heaven may forgive you your sins."
so was the significance for God to show us that if we have true faith anything can happen!? but why would this prove it could happen? i mean didn't they already know he was God? so wouldn't they just assume it's because he was perfect? hmmm... i'm very curious... God does everything for a reason, i don't doubt that. i guess that's an example oh faith i wouldn't think God would use... or something...
ok that's all for now, time for homework