Question: How does the carbon cycle start and end with?

Jordan Kirby answered on 15 Mar 2019:

Hi Zainab!
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Well first things first its a cycle so it technically does not have a start or finish. But if i had to hazard a guess on where it began based on the history of the planet i would likely say that the first part of the cycle would have started when the earliest cyanobacteria would have taken carbon from the atmosphere during a period known as “The great oxygenation event”. So the begining of the cycle would be moving carbon from the atmosphere.
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I guess the end of it would be the death of all organisms that can utilize carbon dioxide. Since the organisms would die it would mean that the carbon wpuld be locked in their decaying biomass and would then be used by sapotrophic fungi and bacteria (fancy way of saying organisms that eat decaying matter) as a food source which would produce more gaseous CO2 returning it to the atmostphere. So both the begining and this hypothetical end would be the atmosphere! Hope that helped ☺