Bass Riff # 1:

G ----------------------|
D -2-2-2-2--------------|
A ---------2--2---------|
E ---------------3--0-0-|

Bass Riff # 2 (which is supposed to be played extremely fast)

G --------------------|
D -------0-5-2p0h2----|
A ---0h2--------------|
E -3---------------0--|