Plant Power: Photosynthesis
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flagWhat you'll discover
- arrow_forwardState the three inputs of photosynthesis: light, water, carbon dioxide
- arrow_forwardName the two products: glucose (sugar) and oxygen
- arrow_forwardExplain why leaves are green and where chlorophyll lives
- arrow_forwardConnect photosynthesis to the oxygen in every breath you take
A leaf is a tiny factory
Plants are extraordinary: unlike animals, they can make their own food out of thin air, water and sunlight. The process is called photosynthesis, and it happens inside the leaf in tiny green structures called chloroplasts. The recipe, written as a chemical shorthand, is: carbon dioxide + water + light energy → glucose + oxygen.
In the simulation you can drag the three ingredients into a leaf and watch green chloroplasts light up as they assemble sugar molecules, releasing oxygen as a gift to the rest of the planet. Without photosynthesis there would be no food chain and no oxygen to breathe — plants literally feed the world.
Why are leaves green?
Leaves look green because of a pigment called chlorophyll, packed inside those chloroplasts. Chlorophyll's superpower is that it is brilliant at soaking up red and blue light from the sun — but it reflects green light straight back, which is why that is the colour your eyes see.
The energy chlorophyll captures is what powers the whole sugar-making reaction. When autumn comes and a tree reclaims the chlorophyll from its leaves, the hidden yellow and orange pigments that were there all along finally show through. So a leaf's green is really the light it could not use.
The oxygen you breathe
Animals and humans breathe in oxygen and breathe out carbon dioxide. Plants do something beautifully complementary: they take in that carbon dioxide, use the carbon to build sugar, and release the oxygen right back. A single large tree can supply a day's oxygen for four people.
This is why forests are sometimes called the lungs of the Earth — and why cutting them down is dangerous for everyone who breathes. Almost every molecule of oxygen in the air was made by a plant, an alga, or a tiny organism in the ocean called phytoplankton, all running the same photosynthesis reaction.