3. In the 1660s, Flemish physician Jan van Helmont grew a small willow tree in a pot of soil. He added only water to the pot. At the end of five years, he found that the tree had gained 75
kilograms, but there was very little change in the mass of the soil. Van Helmont concluded that
the plant gained weight directly from the water. We now know that this conclusion is only
partially correct because, in addition to water, photosynthesis also requires
(1) oxygen from the atmosphere
(2) proteins from animal prey
(3) carbon dioxide from the atmosphere
(4) carbohydrates from the soil