Scientists in different part of the world have conducted expirements to find the speed of light in vaccum. if the result of the expirement are identical they would most likely be valid, biased, unreliable, or non observable

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

i think its control and coordinate because im pretty sure thats what tissue does and the joints are what control movement and then your skeletal/ bones provides portection. hope that .