I just bombed this test and i have 1 retake left. please help!!

Answer:
Hey!
Your answer is CO-ENZYME!
Explanation:
What do CO-ENZYMES do?
They are an organic (but not protein based) compound...they act in a reaction by assisting the enzymes to bind and react with another substance...this then makes the reaction even faster!
But they cannot ever work by themselves to catalyse a reaction!