Humans, birds, whales, and lizards all have similar arm bones. This is an example of what type of structure?

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

frogs. the lower the ph the higher the acid content. frogs have the highest tolerance in this scenario.