Key Idea.
Section 1
The Soil Myth: Evidence from Mass
It looks like plants are built from the soil they grow in, but looks can be deceiving. Experiments show that if you weigh a pot of soil before and after a tree grows huge, the soil's weight barely changes.
This is strong evidence that plants do not "eat" soil to grow. The soil provides small amounts of vitamins, but it is not the main source of the plant's weight. The heavy mass of a tree trunk comes from somewhere else entirely.
Section 2
The Real Ingredients: Air and Water
If plants don't eat soil, what are they made of? They build their bodies using two invisible or simple ingredients found in their environment.
First, plants use their roots to absorb water from the ground. Second, they take in a gas called carbon dioxide from the air. These two materials—water and air—are the primary ingredients a plant uses to build its stems, leaves, and roots.
Section 3
Creating Matter from "Thin Air"
It seems like magic, but plants turn gas and water into solid wood and leaves. When a plant grows, it is actually turning air and water into new matter.
The plant combines these ingredients to create structures like thick branches and green leaves. So, when you look at a giant tree, you are actually looking at a lot of air and water that has been transformed into solid plant body parts.
Expand to review the lesson summary and core properties.
Section 1
The Soil Myth: Evidence from Mass
It looks like plants are built from the soil they grow in, but looks can be deceiving. Experiments show that if you weigh a pot of soil before and after a tree grows huge, the soil's weight barely changes.
This is strong evidence that plants do not "eat" soil to grow. The soil provides small amounts of vitamins, but it is not the main source of the plant's weight. The heavy mass of a tree trunk comes from somewhere else entirely.
Section 2
The Real Ingredients: Air and Water
If plants don't eat soil, what are they made of? They build their bodies using two invisible or simple ingredients found in their environment.
First, plants use their roots to absorb water from the ground. Second, they take in a gas called carbon dioxide from the air. These two materials—water and air—are the primary ingredients a plant uses to build its stems, leaves, and roots.
Section 3
Creating Matter from "Thin Air"
It seems like magic, but plants turn gas and water into solid wood and leaves. When a plant grows, it is actually turning air and water into new matter.
The plant combines these ingredients to create structures like thick branches and green leaves. So, when you look at a giant tree, you are actually looking at a lot of air and water that has been transformed into solid plant body parts.