It is 2018, in New Orleans; and Drew Brees is busy leading the Saints to the NFC championship. While he is playing, he exhales carbon dioxide, and inhales oxygen. This oxygen reacts with glucose to form ATP in a process called cellular respiration
The CO2 from Drew Brees makes its way over to this orange tree. The tree absorbs this, along with light energy and water, and begins photosynthesis in the chloroplasts. This process makes glucose, which will help make the food for the plant to survive.
Fermentation constantly breaks glucose. and allows glycolysis to make small amounts of ATP (anaerobic respiration). This energy, along with the ATP that comes from mitochondria during aerobic respiration, keep our cells energized
Just like humans breath out CO2, photosynthesis produces oxygen that plants release for us humans to breath; kind of like returning a favor
So now these oranges, that absorbed Drew Brees's CO2, are right in front of me, releasing oxygen.
So these oranges we're eating have CO2 that came from Drew Brees, and we're eating them.