How would the burning fossil fuels upset the balance of the carbon dioxide cycle?

The carbon that is found in fossil fuels does not cycle through the earth, rather it is stored  locked in these fossil fuels.

When human beings burn fossil fuels, the stored carbon is released into the atmosphere as carbon dioxide. Once this happens, the carbon in the CO2 is then free to cycle through the earth and can thus upset the natural balance of carbon available, disrupting the way the natural process of carbon cycling occurs.

The carbon that is in storage should remain in storage unless released by purely natural means and not by unnatural actions of human begins.

an active site is a region that is present on an enzyme where the reactants or the substrate molecules we can say bind and experience a chemical reaction. the substrate is basically a reactant whose concentration is changing and that is converting into a product after binding at the active site of an enzyme

the unequal cytoplasmic division that  results  in  one egg  and three polar bodies ensures that a fertilized  egg has  ample nutrients  forits journey  to  the uterus.