A scientist observed that during the course of a chemical reaction the number of ATP molecules were converted into ADP. What did the scientist most likely learn from the observation? a The reaction caused an output of energy. b The reaction produced water. c The reaction consumed water. d The reaction required an input of energy.

Adenosine triphosphate, commonly known as ADP, is an high-energy storage molecule in living cells. It stores and transfers needed energy for metabolic activities. ATP stores its energy in the bonds that hold the phosphate group in its structure. However, the energy is released for use during metabolic processes when the phosphate bond is broken, leading to the release of ADP molecule.

In this case, a scientist observed that during the course of a chemical reaction the number of ATP molecules were converted into ADP. This means that the reaction has caused ATP molecules to release its stored energy i.e. an energy output.