if plants use photosynthesis, how much of fruit is made from sunlight?
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Plants use photosynthesis and sunlight to extract carbon from the carbon dioxide in the air. They then use that carbon to build their bodies, including fruits. So none of the fruit is made from sunlight, though most of it is made from air.
Sunlight provides none of the mass of the fruit. Sunlight provides the energy necessary to create or re-arrange the chemical bonds between carbon, hydrogen, and oxygen to create carbohydrates (sugars, starches, and the cellulose that plants use for structure).
Essentially none of it… It’s made of earth, air and water.
You could argue that there’s an insanely small amount of sunlight in the energy of the chemical bonds of the photosynthesised carbohydrates, but that’s a stretch.
Sunlight contributes **energy**, not **mass**. It is used to create chemical bonds between parts of the air, the water, and the nutrients that the plant consumes (which would otherwise not form bonds by themselves). The energy is then *stored* in the form of chemical bonds.
If you lift up a book and put in on the shelf no “part” of you is now part of the book, you just helped to raise it to a higher energy level by doing mechanical work to *store* potential energy in it.
Imagine I get all my energy from eating potatoes. With that energy I build bidets. How much of the bidet is made from potato?
Me, potato, and bidet are as plant, sunlight, and fruit in your example.
Plants *transform* the energy from sunlight, store it, and use it to build something new.
So insofar as there’s any truth to the fruit being made from sunlight, well it’s important to realize that its not made of sunlight. It’s made using energy harvested with photosynthesis, like my bidets are made with energy harvested through gorging myself on potatoes
The fruit, and most of the tree is made from the air. The tree takes stuff from the air and uses sunlight to turn it into tree stuff.
Sunlight is just the energy source plants use to drive chemical reactions in the same way we use electricity to do lots of stuff. They use that energy to break down water and CO2 and use the carbon, oxygen and hydrogen that comes out of that to make sugar. The sugar is made of carbon, oxygen and hydrogen, not sunlight.
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