Final answer:
The experiment conducted by Jan Baptista van Helmont demonstrated that plant growth was not solely reliant on soil, considering the substantial increase in the willow tree's weight while the soil weight barely changed.
Step-by-step explanation:
The Jan Baptista van Helmont experiment was a significant milestone in biology that offered insights into plant growth and the origins of biomass. Van Helmont planted a willow sapling in a pot of soil and weighed them both. After five years, he found that the tree had gained significant weight while the soil had lost only a negligible amount. Initially, he concluded that the plant's weight gain must be due to the water alone, since that was the only substance he had added to the pot. However, this experiment indirectly demonstrated the role of air in the growth process and thus the fundamental aspects of photosynthesis.<\p>
While van Helmont did not fully understand the process, his work was an important stepping stone towards the discovery and understanding of photosynthesis. The experiment provided evidence that plants did not acquire their mass solely from the soil, implicitly suggesting that other factors, like air and water, played a significant role. Later discoveries attributed the weight gain to carbon dioxide from the air being converted into organic material by the plant, using photosynthesis.<\p>
Regarding essential nutrients for plants, macronutrients and micronutrients are vital for their growth and health. Macronutrients are used in larger quantities and include nitrogen and phosphorus. Micronutrients are needed in smaller amounts and examples include iron and zinc. These elements play critical roles in various physiological and biochemical processes in plants including chlorophyll production and enzyme function.<\p>