That’s an interesting and important question!
Animals, like humans, need oxygen in order to
build tissues and organs. For example, without
oxygen we wouldn’t be able to develop our muscles,
bones, and vital organs like the heart.
The opposite it true for plants. The majority
of a plant’s biomass comes from carbon dioxide
that is absorbed from the atmosphere. Carbon
dioxide (CO2) enters the plant through
tiny pores in the leaves. These pores are called
stomata. Inside the leaf, the plant uses energy
obtained from sunlight to capture CO2
and uses it to build a carbohydrate molecule
called glucose. The glucose is then used to make
other carbohydrates (like cellulose) that comprise
the plant body. Plants harness the energy of
the sun to capture CO2 and build their
tissues and organs (roots, leaves and stems); this
process is called photosynthesis. Without
CO2 photosynthesis just wouldn’t happen
and the plant would not be able to survive.
So when an oak grows from an acorn into a huge
tree, the carbon that comprises the trunk, leaves,
and roots all comes from CO2 in the
atmosphere, which is pretty amazing!
Plants use the carbon from carbon dioxide to
build their bodies, just as you use the carbon
from the food you eat. Unlike plants, you also
gain your energy from the food you eat; plants get
their energy from sunlight, but they still need