Carbohydrate synthesis may be a sub-field of chemical science involved specifically with the generation of natural and unnatural macromolecule structures. This may embody the synthesis of saccharide residues or structures containing over one saccharide, called oligosaccharides. The dark reactions use nucleotide and NADPH to convert CO two into macromolecule. The primary step is fixing CO two into organic carbon. The fundamental reaction is addition of CO two to a phosphorylated acceptor. This step needs no direct input of energy. 2 forms of plants exist, that use completely different acceptor molecules. In so‐called C‐3 plants, the acceptor may be a 5‐carbon, doubly phosphorylated acceptor, and 2 3‐carbon phosphorylated compounds area unit shaped. In C‐4 plants, the acceptor is phosphoenolpyruvate, and therefore the carboxylation makes the 4‐carbon acid oxaloacetatic acid and releases orthophosphate. The nucleotide and NADPH from the sunshine reactions area unit used for creating the acceptors and changing the primary merchandise into aldohexose.