Rough endoplasmic reticulum is the site of the synthesis of proteins destined for export from the cell.
You would still have 651 g of a certain compound but in different products, so the splitting of water via electrolysis you still have 2 Hydrogen and 1 Oxygen.
Primary function of the carbon cycle is to "recycle carbon throughout the biosphere, which includes the atmosphere" Hope this is what you needed!
The temperature would be the independent variable because it is what is being changed or controlled to test the effects.