Photosynthesis

“A leaf does not eat light: it uses photons to drive electrons and build energy-rich molecules.”

01 / PLAINLY

What it means, plainly

Photosynthesis converts light energy into chemical energy and uses inorganic carbon to build organic compounds.

02 / CONTEXT

A little more

Light reactions generate ATP and reducing power; carbon-fixation cycles then incorporate CO₂ into organic molecules. Plants, algae, and certain microbes perform variants of the process.

03 / WHY IT MATTERS

Why it matters

It supports much of Earth's food web and transformed the atmosphere through oxygenic photosynthesis.

04 / EXAMPLE

A familiar example

Oxygen released by plants comes from water split during light reactions, not from carbon dioxide.

05 / LIMIT

What it does not mean

Plants do not obtain most of their mass from soil, and they do not stop respiring when light is available.

06 / NOTICE

Notice it in your day

Draw four inputs or outputs—light, water, CO₂, and oxygen—and mark which stage connects each one.

FINAL NOTE

The idea worth keeping

Track energy, electrons, carbon, and oxygen separately so their routes do not blur together.

QUESTIONS / 02

Questions people still have

Does photosynthesis directly make glucose?

Its cycles produce three-carbon molecules that can later be used to form glucose and other compounds.

Do only plants perform photosynthesis?

No. Algae, cyanobacteria, and other microbial groups capture light through varied pathways.