<P> Although photosynthesis is performed differently by different species , the process always begins when energy from light is absorbed by proteins called reaction centres that contain green chlorophyll pigments . In plants , these proteins are held inside organelles called chloroplasts , which are most abundant in leaf cells , while in bacteria they are embedded in the plasma membrane . In these light - dependent reactions , some energy is used to strip electrons from suitable substances , such as water , producing oxygen gas . The hydrogen freed by the splitting of water is used in the creation of two further compounds that act as an immediate energy storage means : reduced nicotinamide adenine dinucleotide phosphate ( NADPH ) and adenosine triphosphate ( ATP ) , the `` energy currency '' of cells . </P>
what is the source of electrons during photosynthesis
suitable substances , such as water