In the 1600s, a Belgian Physician Named Jan Baptista Van

In the 1600s, a Belgian physician named Jan Baptista van Helmont ran an experiment on a young willow tree.He measured the tree's mass as well as the mass of the pot and soil he planted it in.van Helmont placed the tree in a well-lit spot and watered it periodically.After 5 years, he found that the mass of the plant had increased by 75 kilograms (165 pounds).The pot and soil together did not change significantly in mass.Some of the plant's increase in mass was due to water, but not all of it.Plant growth results from an increase in plant cells as well as extracellular materials that are made up of proteins, lipids, and carbohydrates.The source of carbon that went into constructing these molecules in van Helmont's willow tree was _______.