Answer:
Step-by-step explanation:
The hydrogen that is used in Stage 2 of photosynthesis comes from the water molecules that were originally split in Stage 1. During Stage 1, which occurs in the thylakoid membranes of the chloroplasts, water molecules are broken down into oxygen, protons (H+), and electrons (e-). The oxygen is released into the atmosphere, while the protons and electrons are carried by the electron carrier NADP+ to the stroma of the chloroplasts, where they participate in Stage 2 of photosynthesis, also known as the Calvin cycle or light-independent reactions. In Stage 2, the hydrogen atoms from NADPH are combined with carbon dioxide to create carbohydrates using energy from ATP produced in Stage 1. So, the hydrogen that is used in Stage 2 of photosynthesis ultimately comes from water molecules that were originally split during Stage 1.