The answer is D. Hope this helps!
True. A protein becomes functional only when it reaches its tertiary shape (3D). It is not necessary for the protein to reach the quaternary stage, but that is just a more complex functioning protein. It really is just two tertiary merged together. Example is red blood cells.
In exothermic reactions, the products have higher energy than the reactants, and in endothermic reactions, the reactants have higher energy than the products.
