Why did Gelfand resign against Anand in the shortest match in WCC? I saw the notations of the match in chessbase, and I couldn't understand why Boris resigned. Anand was no where close to checkmate. I don't see why he didn't just trade his queen for a bishop and continue and maybe force a draw.

More importantly, resigning gives away the advantage he got by winning the previous match. Can someone explain what Anand should have done to checkmate Gelfand from the final position ? I can't see it.
http://www.chessgames.com/perl/chessgame?gid=1666558 the shortest game is World Championship history.  It's not so much the material difference, after Bd3 Qxb1+ two Rooks is not enough for the Queen and the Bishop, but the weakness around the Black King will cause Gelfand to lose anyway.  After h6 and Ne4, d6 will fall and mate is always possible on g7.  A thorough annotation is at http://www.ajschess.com/lifemasteraj/FIDE_World-Champ-2012_game-eight.html 


[fen ""]

1.d4 Nf6 2.c4 g6 3.f3 c5 4.d5 d6 5.e4 Bg7 6.Ne2 O-O 7.Nec3 Nh5
8.Bg5 Bf6 9.Bxf6 exf6 10.Qd2 f5 11.exf5 Bxf5 12.g4 Re8+ 13.Kd1
Bxb1 14.Rxb1 Qf6 15.gxh5 Qxf3+ 16.Kc2 Qxh1 17.Qf2