6CO2 + 6H2O + light C6H12O6 + 6O2 C6H12O6 + 6O2 6CO2 + 6H2O + energy How do these equations explain why the total amount of O2 and CO2 remains the same?

They cancel each other out. There are 12 Carbon molecules on each of the equation and 54 Oxygen on each side So their carbons cancel each other out on each side of the equations as the oxygen.

hope it helps

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.