Fill in the Blank Questions 23.The site where a signal molecule binds to the surface of an enzyme is the ______________ site. 24.The study of energy is called _____________. 25.A ball sitting on a table top has __________ energy because of its position. 26.When an endergonic reaction is driven by the splitting of ATP molecules, such that both these reactions occur simultaneously, the two-part reaction is called a _____________ reaction. 27.If a ball begins to roll down an incline, its ________ energy is converted into _______ energy. Â Â