8.1 Energy and Life
8.2 Photosynthesis: An Overview
8.3 The Process of Photosynthesis
OUT OF THIN AIR?
One of the earliest clues as to how photosynthesis works came from a simple study of plant growth. When a tiny seed grows into a massive tree, where does all its extra mass come from? More than 300 years ago, a Flemish physician named Jan van Helmont decided to find out. He planted a young willow tree, with a mass of just 2 kilograms, in a pot with 90 kilograms of dry soil. He watered the plant as needed and allowed it to grow in bright sunlight. Five years later, he carefully removed the tree from the pot and weighed it. It had a mass of about 77 kilograms. Where did the extra 75 kilograms come from? The soil, the water—or, maybe, right out of thin air? As you read this chapter, look for clues to help you discover where the willow tree's extra mass came from. Then, solve the mystery.
Never Stop Exploring Your World.
Understanding Jan van Helmont's experiments is just the beginning. Take a video field trip with the ecogeeks of Untamed Science to see where this mystery leads.