Photosynthesis is a complex process divided into two stages by plant biologists. The first stage is the light-depended reaction, while the second stage is the light-independent reaction or dark reaction.
In the first stage, light energy is trapped by the chloroplast and converted into chemical energy contained in adenosine triphospate, abbreviated as ATP, and nicotinamide adenine dinucleotide phosphate, abbreviated as NADPH. These two molecules are normally used in stage two of the photosynthesis process.
In the second stage, the hydrogen atoms that assist in the formation of glucose are provided by NADPH, while the energy needed to carry out this process and other reactions for synthesizing glucose are provided by the ATP. The first stage of photosynthesis normally depends on the flow of the electrons and energy initiated by light energy.
When the photosystem I pigments are stricken by light and their electrons are excited, the photosynthesis process begins. The swift energy moves from molecule to molecule until it reaches P700, a special chlorophyll molecule. This special molecule uses the energy from the excited electrons to heighten its electrons to a higher energy level that enables them to be captured by an adjoining electron acceptor molecule.