Rangers came into the match 15 minutes in, resulting in a shot for David Templeton from the edge of the box, but his powerful effort failed to find the target.
Bilel Mohsni had a chance shortly before half time when he collected the ball from a throw-in, but the defender's effort comfortably cleared the crossbar.
Bell was called into action again from the resulting corner, clearing from David McCracken heading from close range.
The visitors finally managed to break the deadlock inside the final 15 minutes when a deflected Lewis MacLeod shot wrong-footed MacDonald to give Rangers the lead.
Rangers needed just six minutes to double their lead as a cross fell to Nicky Clark at the post to leave him with an easy finish from close range, putting the win beyond doubt for the visitors.