Why do living cells need catalytic enzymes?

Answer 1

First of all living cells use catalysts (more specifically - enzymes), because without them it would need an extremely long period of time for all of the biochemical reactions to finish. Of course, enzymes are not the only thing which may change the speed of the reaction - if the environmental conditions (temperature, pH, pressure and others) are changed the reactions also may start to run faster. But the change of these conditions may kill the organisms or reduce their fitness. For instance, if the temperature becomes higher - yes the reactions would start to run faster. But the nucleic acids and the proteins of the organism are going to denature (their normal folding processes are going to be disrupted), so this eventually would kill or damage the organism (that is what happens when a living tissue is burnt).

Answer 2

Living cells need catalytic enzymes to speed up chemical reactions that are essential for their survival and function. Enzymes lower the activation energy required for these reactions, allowing them to occur at a much faster rate than they would without the enzyme. This enables cells to maintain homeostasis, generate energy, build and repair structures, and carry out other necessary processes efficiently.