Photosynthesis biology lesson for kids: 1st, 2nd, 3rd, 4th, 5th, 6th and 7th grades biology lesson.
Photosynthesis is an extremely important process for life on the planet Earth. It is the process by which plants and a few other organisms, both small and large, convert light energy into chemical energy, which living things (including the photosynthesizing organisms) can then use. The word has two parts: “photo” means “light”, and “synthesis” means “to put together”. What being put together? We will see!
Photosynthesis is a chemical reaction. It can be written out like this:
6CO2 + 6H2O + light energy à C6H12O6 + 6O2
That means 6 carbon dioxide molecules and 6 water molecules combine (are put together) with the help of light energy to produce 1 glucose molecule and release 6 oxygen molecules. This reaction is very important because for many reasons. For one, living things release carbon dioxide when they respire (release energy from sugars like glucose), so plants help to reduce the amount of carbon dioxide in the air. That’s good because if there’s too much, it would be toxic for us, and it would also cause the Earth to heat up too much. Also, most living things on Earth (including plants!) use oxygen to respire, so photosynthesizing organisms provide the world with this necessary gas.
Plants also use glucose for a lot of different things. They make cellulose for their cell walls (the tough layer around their cells) from it, and make lots of different kinds of sugars and bigger molecules.
Where does photosynthesis occur? It usually happens in the leaves of plants, because they have such a high surface area for absorbing light and carbon dioxide. Leaves have small openings called stomata (singular: stoma) through which the oxygen necessary for photosynthesis can enter. Photosynthesis also happens in other places, too, like the stem, especially when the plant is young. As a general rule, any green part of the plant photosynthesizes.
There’s more to it, though. Photosynthesizing plant cells have organelles called chloroplasts. They contain a green chemical called chlorophyll. Chlorophyll is important because it is responsible for absorbing light energy for the chloroplasts to use to make glucose.
Photosynthesis is important not only for the plants and other animals that do it, but other organisms, too. You see, animals and other organisms eat the photosynthesizers, and that is how they get the energy they need to survive. There are even animals that have symbiotic relationships with photosynthesizers. For example, corals have small algae in their bodies, which provide the corals with energy. Without them, the corals can’t survive!
Believe it or not, photosynthesis from years ago is still in chemical form even today! Fossil fuels (coal, gas, and oil) is made from the broken-down bodies of long-dead plants, and that gives us the energy we need to move our cars around, and even make electricity to power our towns and cities!