a nucleotide, CHNOP, present in, and vital to the energy processes of, all living cells: during biological oxidations energy is stored in the ATP molecule as ADP is. Photosynthesis, Respiration, and the ATP-ADP Cycle Clovis O. Price Jr. Lucy Flower High School 3545 W. Fulton Chicago IL 60624 (312) 535-6755 ADP's role is to provide a source for making ATP. ADP, together with free phosphate, can form ATP, which is the molecule that the cell uses as its immediate source of. Craig Beals explains how ATP and ADP cycle during Photosynthesis. The following are examined: ATP, ADP, Chlorophyll, Chemical Energy, Cells, Phosphate. PHOTOSYNTHESIS Table of Contents What is. is the process of converting energy from a light-excited electron into the pyrophosphate bond of an ADP molecule. These two stages of photosynthesis. light reactions also generate ATP by powering the addition of a phosphate group to ADP, a process called. ADP. Definition. noun. Abbreviation for adenosine diphosphate, a nucleotide essential in photosynthesis and glycolysis. Supplement. Compare: AMP, ATP. ATP stands for Adenosine Tri-Phosphate, and is the energy used by an organism in its daily operations. It consists of an adenosine molecule and three inorganic phosphates ADP is an organic compound that is essential for the transfer of energy during photosynthesis. ADP is composed of a five carbon atom compound known as ribose, one. Photosynthesis is a process used by plants and other organisms to convert light energy, normally from the Sun, into chemical energy that can be later released to fuel.