Here's why:

* Photosynthesis: This process uses sunlight to convert carbon dioxide (CO₂) and water (H₂O) into glucose (C₆H₁₂O₆) and oxygen (O₂).

* Light-dependent reactions: This is the first stage of photosynthesis. Light energy is captured by chlorophyll and used to split water molecules.

* Splitting of water: This process, called photolysis, releases electrons, hydrogen ions (H+), and oxygen gas (O₂).

So, the splitting of water is a crucial step in photosynthesis, providing the electrons and hydrogen ions needed to power the production of glucose.