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Building food from air

How Do Plants Eat Light?

Plants use light energy to join air and water into sugar. That is where food starts.

1 Light providesthe energy2 Air and waterare joinedtogether3 Sugar — andoxygen leftover
The only way food gets made on Earth.

  1. Step 1 of 5

    Plants do not eat soil.

    What people assume Trees eat soilWhat is true Most of a tree camefrom the air

    A tree's mass comes overwhelmingly from air, not ground. Soil supplies water and a few minerals; the carbon is pulled out of the atmosphere.

  2. Step 2 of 5

    Leaves take carbon dioxide from the air.

    Air with carbondioxide Enters throughleaf pores

    Tiny pores on the underside of each leaf let air in. Carbon dioxide is the raw material — the actual substance a plant is built from.

  3. Step 3 of 5

    Roots pull water up.

    1 Roots absorbwater2 It risesthrough thestem3 Arrives at theleaves

    Water travels from the roots up through the trunk to every leaf. In a tall tree it climbs over a hundred metres with no pump at all.

  4. Step 4 of 5

    Chlorophyll captures the light energy.

    A green leaf Chlorophyll absorbinglight energy

    The green pigment absorbs red and blue light and uses that energy to break water apart, which is the hard step of the whole process.

  5. Step 5 of 5

    Sugar is the product; oxygen is the waste.

    The plant keeps Sugar — its food andits bodyThe plant discards Oxygen — which webreathe

    Carbon and water are assembled into sugar, and the leftover oxygen is released. Every breath you take is a plant's discarded by-product.

    Almost every food chain on Earth starts here. Nearly all the energy in your dinner was sunlight caught by a leaf.

The short version

Plants use light energy to build sugar from air and water, releasing oxygen as waste.

Try it yourself

Put a leafy sprig in water in the sun. Bubbles collect on the leaves — that is oxygen being made in front of you.

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