1. About 200 years ago, Jan Baptista van Helmont did experiments on the nature of photosynthesis. He wanted to know where growing plants get the materials necessary for increases in size. He planted a tree seedling weighing 5 pounds in a barrel filled with 200 pounds of soil. He watered the tree regularly. Five years passed. Then van Helmont weighed the tree and the soil. The tree weighed 169 pounds, 3 ounces. The soil weighed 199 pounds, 14 ounces. Because the tree gained so much weight and the soil lost so little, he concluded the tree had gained all of its additional weight by absorbing water he had added to the barrel. Given what you know about biological molecules, why was he misguided? Knowing what you do about photosynthesis, what really happened?
2. While gazing into an aquarium, you observe bubbling from an aquatic plant. What is happening?