Cycles in Biology

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Cycles in Biology

Cycles in biology play a fundamental role in the world that we live in. Cycles occur all around and inside of us in many different forms, from the Krebs to the Calvin cycle. There are large scale cycles happening and they are essential in regulating the nutrients and substances that are around us which without, life on earth could no function.

One of the largest cycles that occurs all around us is in everyday life is the carbon cycle. The current atmospheric composition currently consists of approximately 0.04% of Carbon dioxide. A large proportion of it is found dissolved in the oceans as well as the atmosphere. The carbon cycle consists of 6 stages. Initially the CO2 that is absorbed by plants for the use in photosynthesis becomes carbon compounds in plant tissue. The carbon is moved up the food chain by consumption, a primary consumer. It is passed on to the secondary and tertiary consumers when they eat other consumers. When these organisms die they are digested by microorganisms known as decomposers (bacteria and fungi), when these decomposers feed on the dead organism it is called saprobiotic nutrition. The carbon is then released back into the atmosphere and other living organisms which proceed on to respiring and this causes CO2 to be released. However if the dead organism ends up somewhere were there is no decomposers present, then this matter will turn into fossil fuels over millions of years. We will then extract the fossil fuels and use them for energy and as fuels, this process known as combustion is very widely used, it then releases CO2 back into the atmosphere where it once came from.

Another large scale cycle that occurs is the nitrogen cycle. Plants and animals need nitrogen to make proteins and nucleic acids. In the atmosphere there is roughly 78% nitrogen content, but plants and animals cannot use it in that form. Bacteria are required to convert the nitrogen gas into nitrogen compound. The...
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