The dark reactions resemble parts of the glycolytic and gluconeogenesis pathways, sharing with them some of the same intermediates and enzymes. Confusion is avoided by a physical separation, since glycolysis and gluconeogenesis take place in the cytoplasm, whereas the dark reactions are located inside the chloroplasts of a plant cell.

The ability to "fix" C0₂ in organic molecules is one of the oldest and most universal biochemical talents of life. These three glucose pathways appear to be descendants of an extremely ancient carbon biochemistry.