Answer:
Temperature & Presence of any inhibitors or activators.
Step-by-step explanation:
Temperature: Although a higher temperature increases the rate of reaction, enzymes denature after a specific temperature. At different temperatures, the different enzyme works. So, for getting a particular function from an enzyme, proper temperature is needed. If adequate temperature won't present or temperature will fluctuate, the enzyme won't be able to work effectively.
Presence of any inhibitors or activators: When any inhibitors will present during an enzymatic reaction, the enzyme won't be able to work effectively. And if any activators will present, it will completely change the work efficiency of any enzyme.