In just one day, a third set of leaves formed on the plant. The stem and leaves are made of a chemical called carbohydrates. Carbohydrate come from the words carbo and hydrate meaning carbon-water. That is because scientist first analyzed the chemical as C(H20) and they thought it was made of carbon atoms and water atoms. Today, we know the formula is not that simple, but the ratio is still the same, one carbon atom for each water molecule. Where did the plant get the carbon and water? The plant absorbs carbon dioxide CO2 from the air and H2O from the soil. The plant then uses light to combine the carbon and water and give off the O2. How does the plant know how to do that? Who taught the plant to do chemistry?