Directions: Use the information provided and your knowledge of Life Science to answer the following questions. Show all work where necessary.
Directions: Use the information provided and your knowledge of Life Science to answer the following questions. Show all work where necessary.
In the 1600s, the scientist Jan Baptista van Helmont wanted to know where plants get their mass as they grow. At the time, most people believed plants “ate” soil. To test this, van Helmont planted a small willow tree in a pot of measured soil and carefully tracked its mass and the soil mass for five years.
He watered the tree regularly with rainwater and covered the pot to prevent dust from entering. After five years, the tree had gained
This experiment showed that most of the tree’s increase in mass did not come from the soil. Instead, we now know that the tree’s growth came from carbon dioxide in the air and water, which the plant used to build sugars and other compounds through photosynthesis.
Table 1.
Time (Years) | Tree Mass (kg) | Soil Mass (kg) | Water Added (L) |
|---|---|---|---|
0 | 2.3 | 90 | 0 |
1 | 5.5 | 89.99 | 150 |
3 | 22 | 89.97 | 450 |
5 | 76.3 | 89.94 | 750 |
Even though the willow tree’s mass increased by more than
This experiment provided the first evidence that air and water are the main sources of plant mass, not soil. It helps students connect modern photosynthesis concepts with one of the earliest controlled scientific experiments in plant biology.
How does van Helmont’s experiment show that plants get most of their mass from air and water, not soil? Write a claim, give evidence, and explain your reasoning.
What pattern do you see between tree mass and soil mass over the five-year experiment?
Use evidence from the table and graphs in your answer.
What do plants use to make the sugars that increase their mass?
Which observation from van Helmont’s experiment best supports the idea that soil is NOT the main source of plant mass?
Explain how photosynthesis helps plants grow even though they use very little soil mass.