What is the Carbon Cycle?
Organic compounds contain carbon dioxide (CO2) in their air and HCO3 and CO3— ions in water sources of carbon. Green plants get CO2 from the air and use it during photosynthesis to make glucose and other carbohydrates. Marine plants use CO2 dissolved in water along with HCO3 AND CO3—ions. The plants use their food (glucose) for their own growth and development. Animals also get their food from plants.
The energy of food (glucose, protein, or lipids) is released by living organisms in respiration or decomposition. This energy is utilized by the processed glucose is oxidized to release CO2. This carbon dioxide is again used by the plants during photosynthesis and the cycle is completed.
The carbon atom is the principal building block of many kinds of biomolecules. Carbon is found as graphite and diamond in nature. It occurs as carbon dioxide in the atmosphere.
Why is the carbon cycle important?
The carbon cycle is a perfect cycle in the sense that carbon is returned to the atmosphere as soon as it is removed.
Major sources of carbon for the living world are carbon dioxide present in the atmosphere and water. Fossil fuels like peat, coal, natural gas, and petroleum also contain carbon. Carbonates of the earth’s crust also give rise to carbon dioxide.
The major process that brings carbon from the atmosphere or water into the living world is photosynthesis. Producers take in carbon dioxide from the atmosphere and convert it into organic compounds. In this way, carbon becomes a part of the body of producers. This carbon enters food chains and is passed to herbivores, carnivores, and decomposers.
Carbon dioxide is released back to the environment by the respiration of producers and consumers. It is also released by the decomposition of organic wastes and dead bodies by decomposers. The burning of wood and fossil fuels also adds a large amount of carbon dioxide into the atmosphere.
The balance of carbon dioxide is upset by human activities such as deforestation burning fossil fuels. As a result, the amount of carbon dioxide in the atmosphere is increasing, causing the greenhouse effect and global warming.
Of all the chemical elements known to man, perhaps the most interesting one is carbon. Did you know, for example, that in the form of crystal it gives us one of our most valuable gems, the Diamond? As graphite, carbon forms the lead of lead pencils. And coal, the source of much of the heat and power of this machine age, is mostly carbon.
But even more important is the fact that carbon is so vital to life. The bodies of all living things are made up of compounds containing carbon. In fact, scientists believe that where carbon is found in any quantity in the earth, their life has probably existed.
The carbon cycle is the process by which carbon is continuously being removed, used, and replaced by living things. Here is how it works. There is carbon dioxide in the air. Plants secure carbon from this gas and use it in building up their roots, stems, and leaves. Animals get carbon for food from the plants, in the form of vegetables, fruits, or cereals. At the same time, carbon dioxide is being returned to the air, especially by the animals’ breathing, and by the burning or decay of plants. The carbon cycle is thus completed.
When elements combine, we have a compound. The number of carbon compounds that we know so far is enormous – more than 200,000 of them! All the other elements together do not form nearly as many compounds as the single element carbon. The reason for this is that the carbon atom can join with the atoms of other elements in so many different ways and can form rings and chains in combination with other carbon atoms.
You come in contact with or use carbon compounds constantly in your daily life. You breathe in a little carbon dioxide and breathe out much more. And most fuels, foods, drugs, plastics, perfumes (and dozens upon dozens of other products) are carbon compounds!