Which gas has recently increased in the mesosphere, creating a rise in water vapor which has led to the formation of high-altitude clouds that are visible at night? A) Ozone
B)Methane
C)Carbon Dioxide
D)Hydrogen

I'm not 100% sure but I'm positive the answer was or is Methane, correct me if I'm wrong!

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 generally accepted parts of modern cell theory include: all known living things are made up of one or more cells. all living cells arise from pre-existing cells by division. the cell is the fundamental unit of structure and function in all living organisms.