Final answer:
During the oxidation of glyceraldehyde 3-phosphate (G3P), a hydrogen molecule is removed, resulting in the reduction of NAD+ to NADH.
Step-by-step explanation:
The oxidation of glyceraldehyde 3-phosphate (G3P) produces 1,3-diphosphoglyceric acid (1,3diPG) and reduces NAD+ to NADH. In this process, a hydrogen molecule (H2) is removed from G3P, which splits into a hydride ion (H-) and a proton (H+). The H- ion reduces NAD+ to NADH, while the proton remains in solution.