Green plants use the process of photosynthesis to make carbohydrates. Using sunlight as the energy source, plants can change water, carbon dioxide and minerals into oxygen and glucose. Not only do plants depend on photosynthesis for survival and growth, humans depend on plants and photosynthesis, also. Photosynthesis makes the oxygen needed by humans and animals. As the cycle continues, humans and animals will also provide the carbon dioxide that plants need for photosynthesis.
As a plant grows in the soil, moisture falls on and around the plant in the form of rain or supplementary watering from a watering can. The plant's roots absorb the water and move it throughout the roots, stems, and leaves. Instead of veins to transport water through plants, plants have xylem that serves the same purpose. The plant also takes in carbon dioxide through the leaves. Leaves contain chlorophyll, which gives them a green color. Chlorophyll also works to trap the sun's energy so the plant can use it. Plants use a special mixture of the molecules in carbon dioxide and water, along with energy from the sun, to make the carbohydrates needed for life and growth. These carbohydrates -- also called glucose -- help the plant to give off oxygen into the air through the leaves. Plants also place some of these carbohydrates into storage, which they can use later, if necessary.
Photosynthesis happens in chloroplasts within plants, which typically are found in the green parts. Other parts, like the flower petals in a peony bouquet, would not have chloroplasts, and do not collect energy this way. Chloroplasts are organelles in plants and some algae. Chloroplasts are responsible for making food within cells. Special membranes within the chloroplast collect chlorophyll molecules. A reaction happens when energy from the sun combines with these molecules, which makes photosynthesis possible. These compounds move through the chloroplast to finish the process of photosynthesis.
The definition of "photosynthesis" is "putting together with light." Photosynthesis needs special factors to exist for it to happen. The temperature of the air, the strength of the sunlight, the wavelengths of the light, and the amount of carbon dioxide present around the plant are factors that determine the amount of photosynthesis that can happen in a plant. The chemical equation necessary for photosynthesis is complicated, requiring a specific mixture of molecules for the process to happen.
Plants have no use for oxygen, so they release it through their leaves. In this way, oxygen is a byproduct of photosynthesis. Plants use some of the carbohydrates produced by photosynthesis as fuel for the respiration process. Respiration involves releasing oxygen into the environment. Plants will store other carbohydrates that they don't use for respiration. If the plant needs these stored resources later, it can transform them back into glucose and use it then.
Light energy from the sun is the driving force behind photosynthesis. Light provides the energy necessary for plants to convert water and carbon dioxide molecules into carbohydrates. Sunlight contains a combination of different rays, including visible light rays, ultraviolet rays, and infrared rays. The rays needed for photosynthesis are the visible light rays, which contain every color of the rainbow. The blue and red wavelengths are the most important for photosynthesis, because these wavelengths absorb into plant leaves most effectively. Other wavelengths, such as green ones, do not absorb as efficiently. Because all life is dependent on photosynthesis and its byproduct (oxygen), all life is dependent on the sun and the energy it provides.
Photosynthesis requires two stages for completion -- the light dependent process and the dark reaction process. The light dependent process happens first, and then the dark reaction process follows. In the light dependent process, light from the sun enters the chloroplast to begin the chemical process. As this occurs, water and carbon dioxide combine in the plant and the water molecules begin to break up. The dark reaction process received this name because this process does not require light. The dark reaction process also occurs in the chloroplast, as water and carbon dioxide molecules continue to combine. The dark reaction finishes the production of carbohydrates to keep the plant alive and healthy.
Not only does photosynthesis keep plants alive, which produces oxygen for humans and animals, photosynthesis has other far-reaching effects on life. Plants produce food, which keeps humans and animals alive. Plants also produce fossil fuels, which humans need to survive. Burning wood is a direct result of trees, which exist due to photosynthesis. Additionally, other fossil fuels such as coal are a direct result of ancient plants that existed thanks to photosynthesis.
Written by Ava Rose