Wood, when dry, stores chemical energy. This chemical energy is released as the wood burns, and it is converted into heat, or thermal energy. This also produces light energy. As a result of burning, the wood turns into an entirely new substance - ashes. Wood, a form of fuel with lots of potential energy stored in its covalent bonds, will react with molecules of oxygen in the air in a dramatic chemical reaction we call fire. The complex molecules in the wood have 'high energy' covalent bonds, as do the molecules of oxygen. I hope this helped:))
I believe the experiment was too see if the flowers that would grow from the stem would turn out to be red in color. (Which is the reason they put red ink.)
The carbon cycle is nature's way of reusing carbon atoms, which travel from the atmosphere into organisms in the Earth and then back into the atmosphere over and over again. Most carbon is stored in rocks and sediments, while the rest is stored in the ocean, atmosphere, and living organisms.