NOVA Online | Methuselah Tree

Illuminating Photosynthesis
Intro | The Cycle | Atomic Shuffle | Three Puzzlers

Diagram: tree

Photosynthesis, the trapper of sunlight;
it's needed for life to subsist.
All plants use the process to make food;
without it most life would desist.

Diagram: H20 molecules

The process begins with plain water
but not from the tap does it flow.
Some water is made within leaf cells
and some is sucked up from below.

Diagram: H molecules and O2 molecules

With energy gained from sunlight,
the Hs are stripped from each O.
The oxygen atoms form twosomes,
and out of the leaf they all go.

Diagram: H molecules and CO2 molecules

Meanwhile CO2 has just entered
through holes in the leaf called stomata.
The gas is exhaled by Earth's creatures,
including all invertebrata.

Diagram: H molecules, H2O molecules, and CO molecules

Diagram: H molecules, H2O molecules, and CO molecules

CO2 taken in goes through changes;
its atoms get pulled to and fro.
It loses an O, which sticks to two Hs;
together they form H2O.

Diagram: glucose molecule

But the plant has a goal that is bigger in scope;
it's out to make food it can keep.
It builds a big structure of Cs, Hs, and Os;
it's glucose, and boy is it sweet.

Diagram: glucose molecule with reaction formula

Diagram: glucose molecule with reaction formula

Some folks get a kick from equations,
which explain things by some kind of law.
If by chance you are one of these people,
then this explains what you just saw.

12H₂0 + 6CO₂ * C₆H₁₂O₆ + 6H₂O + 6O₂

Note about this equation

12H₂0 + 6CO₂ * C₆H₁₂O₆ + 6H₂O + 6O₂

Sometimes the above formula is shown with six H2Os on the left side and no H2Os on the right side (6H₂O + 6CO₂ * C₆H₁₂O₆ + 6O₂). This is a simpler way of looking at the process—one that doesn't take into consideration, as this feature does, that the oxygen released through photosynthesis comes only from water molecules.

The Cycle
Three Puzzlers

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