In biological systems, the chemical reactions concerning glucose and ATP as a product are vital for cellular respiration and photosynthesis. Shortcuts reduce the activation energy, which increases the net "gain" of products. I would go with the last one.
Answer:
The ozone layer is being depleted due to CFC's. CFC's are found in aersoal spray cans and refrigants, when they are released into the atmosphere it causes depletion of the ozone layer. Humans are the one who made the CFC's, causing the ozone layer to deplete, even though they have been banned now, a lot of damage has been done.
Answer from Gauthmath
There is a difference in color between the reactants and the product. Also, a gas and a solid bread loaf were produced, compared to the liquid or powder forms of the reactants.