insulin is known as an endocrine hormone. The endocrine glands are what produce hormones. Insulin is a protein that is made by the beta cells , which are found in the pancreas. Beta cells major function is to store and then release insulin.
Hopefully this helped and good luck. If you need me to clarify anything just let me know.
The substances that are being used up in cellular respiration are oxygen (O2) and glucose (C6H12O6). They are the main reactants. Cellular respiration happens in the mitochondria, the power house of the cell. Hope this answers the question.
The second way is to put wet sand with rocks in the sand in the bottom of the bottle, then put dry sand next, get some water and dump it all in there with the plant in it. The advantages in the first one was the plant gets a good amount of water and cactus love water so that is one advantage.