Here's how it works:

* Sunlight provides the energy for photosynthesis.

* Water (H2O) is absorbed from the roots.

* Carbon dioxide (CO2) is taken in through tiny openings called stomata on the leaves.

* Chlorophyll, a green pigment in plants, captures the sunlight energy.

* This energy is used to split water molecules, releasing oxygen (O2) as a byproduct.

* The energy and carbon from CO2 are then combined to create glucose (C6H12O6), a simple sugar that is a type of carbohydrate.

So, carbon dioxide is the key ingredient, along with water and sunlight, that plants use to build their food supply.