In photosynthesis, plants break apart carbon dioxide (CO2) molecules.

Here's how it works:

1. CO2 is absorbed from the atmosphere through tiny pores in the leaves called stomata.

2. Inside the plant's chloroplasts, CO2 is combined with water (H2O) using energy from sunlight.

3. This process breaks apart the CO2 molecule, and the carbon atoms are used to build sugar (glucose), which is the plant's food source.

4. Oxygen (O2) is released as a byproduct.

So, while plants break apart CO2 during photosynthesis, they also use the carbon atoms from CO2 to build glucose.