Plants and algae can do something that you can’t do: they make their own food! Using photosynthesis, plants make complex food molecules that give us energy. In the process, they also make oxygen. Every time you eat fruits or vegetables, or even meat or dairy, you are also consuming energy that was first captured by plants.
The Ingredients for Photosynthesis
Plants make their own food molecules – sugars called glucose – by absorbing light and combining molecules from the air and from water.
The three ingredients plants need for photosynthesis are sunlight, carbon dioxide and water. Plants get the carbon dioxide they need from the air through pores in their leaves. Their roots draw water from the soil. Plants are filled with chlorophyll, a pigment molecule that can absorb the light they need from the sun.
Making Sugar from Air: How Photosynthesis Works
Step 1: Gather Energy from Light
The chlorophyll pigments capture the energy in light. These pigment molecules then send the energy into a complex system.
Step 2: Store the Energy
Making sugar out of air requires lots of energy! But, plants cannot make sugar as fast as the energy comes in, so the energy is stored in smaller molecules. Water is needed in the process that stores energy. That’s why plants need water. Plus, when plants use up the water, they release the oxygen inside the water molecules. This gives us oxygen to breathe!
Step 3: Combine Carbon Dioxide Molecules
The final step in photosynthesis is the process of combining carbon dioxide molecules together. Using the energy the plant stored earlier, the molecules of carbon dioxide are combined together to make sugar molecules. Since plants can temporarily store the energy from sunlight, this process can even happen in the dark. Plants are constantly creating new glucose molecules, even at night!
Plants Feed the Whole World!
Even if you don’t like to eat your veggies, you couldn’t survive without plants. You need the oxygen they release during photosynthesis. In fact, all animals need oxygen that plants put into the atmosphere. Animals breathe out carbon dioxide and plants turn that into oxygen and sugar in an endless cycle.
Every food chain starts with plants. Even carnivorous animals that eat only meat, like tigers, rely on plants. Carnivores eat herbivores. Herbivores eat plants. Without the plants, the carnivores wouldn’t survive. Plants are the foundation of all ecosystems on earth.
Written by Laura McCamy
Edited by Gabriel Buckley, MS Professional Natural Sciences
Illustrated by Meimo Siwapon