SSC
BIOLOGY
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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carbon dioxide in the air
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oxygen in the air
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the soil
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water
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Detailed explanation-1: -As the weight of the soil had hardly changed, van Helmont concluded that plant growth cannot only be due to minerals from the soil. He thought that the extra plant material had come from the water alone.
Detailed explanation-2: -Van Helmont thought that his experiment was evidence that water must be food for plants. He thought that if soil and minerals in the soil were not giving the tree its food, then the tree must be gaining weight by getting food from the water. After all, he had been watering the tree everyday for five years.
Detailed explanation-3: -He planted the tree, watered it and then left it for 5 years. He then re-weighed the tree, which had increased in mass by over 12 stone. He dried the soil and weighed it, showing that the soil was almost the same mass. He concluded that the tree grew by drinking water.