Question

what is the effect of a catalyst and inhibitor in an endo and exothermic reaction in terms of activation energy?

Answer 1

A catalyst changes the mechanics of a reaction so the activation energy is lower.
An inhibitor changes the mechanics of a reaction so the activation is higher.

It does not make a difference whether the reaction in question is endothermic or exothermic.

Answer 2

what would that look like on a graph? would the catalyst effect be higher that the normal reaction and the inhibitor be lower than the normal reaction?

Answer 3

The catalyst makes the initial hill (activation energy barrier) lower, while the inhibitor makes that initial hill higher. The starting and ending points on all graphs should remain the same.