[Yo-Yo]

Then as a biochemist you should know that the difference between a product and a byproduct is context. When someone says that plants produce O₂ from CO₂, it is a true statement. In that context, sugars are a byproduct.

[exDemMom]

As I said, oxygen is a byproduct. The plant’s goal in metabolizing CO2 is not to produce oxygen, but to produce sugars, and from there to produce all of the other biomolecules necessary for life. True, plants do use a fraction of the O2 that they produce, for exactly the same purpose that animals use O2. But most of the O2 they produce is a byproduct which they outgas.

Precision, precision.