Photosynthesis

- Ah, isn't this a lovely day! - ... For WHAT? An invigorating walk in the forest, perhaps? I feel full of energy! ... I have no energy at all.

But you've eaten food today? - Yeeeees... - You do remember, right? Both humans and animals need food to get energy! Yeah... but how about TREES! It's not like they eat hamburgers.

No, plants and algae don't need to eat, they get their energy from something called... photosynthesis! Photo-what? To us, the leaves look green because they are full of a substance called chlorophyll. The chlorophyll takes up energy from the sun and uses it to make energy for the plant.

Looking at a cross section of a leaf, we find all the components necessary for photosynthesis. Here is water that has been absorbed via the roots, and carbon dioxide that has been absorbed through small openings underneath the leaves - stomata. Energy from sunlight is caught by small green sections of the cell full of chlorophyll - chloroplasts. Here in the chloroplasts water and carbon dioxide are combined using sun energy and transformed into glucose. At the same time, oxygen is created that animals and plants breathe.

The glucose is stored as starch. Starch consists of 3-400 glucose molecules in a row. Some plants, for example potatoes, store starch in tubers. Other plants, for example wheat, have big stores of starch in their seeds. Plants can also build cellulose out of glucose, which for example makes up tree trunks.

Cellulose consists of more than a thousand glucose molecules. But if there were no plants, wouldn't there be any oxygen to breathe then? No, that's right! Almost all life on earth is dependent on photosynthesis. Without photosynthesis, almost no life!

Some of the oxygen in the atmosphere comes from photosynthesis in land plants, but most comes from algae and from a group of bacteria in the ocean called cyanobacteria. But I still don't get it: how exactly does photosynthesis work then? Green plants take up water through their roots. In the air there is carbon in the form of carbon dioxide, that is taken up by the stomata on the underside of the leaf. In the leaves there are chloroplasts with chlorophyll that transforms the carbon dioxide and water, with the help of sun energy, into oxygen and glucose.

Land plants, algae and cyanobacteria in the ocean can all perform photosynthesis. If photosynthesis is described with a chemical formula it looks like this: Six carbon dioxide molecules, plus six water molecules, plus energy from the sun, turns into six oxygen molecules and a glucose molecule. Cool! So we're really walking around amongst a bunch of factories that manufactures sugar and oxygen! Yeah, that's right!

Very important little factories that are necessary for almost all life on earth. Factories that make the oxygen we breathe and the food we eat!