2.9 Understand how the functioning of enzymes can be affected by changes in temperature, including changes due to change in active site

Enzymes work best at an optimum temperature. This can be different from organism to organism, but in humans, it is about 36 - 38 ºC. 

If the temperature is too low, the enzymes won't have enough energy to speed up the reaction(s) much.

If the temperature is too high, the enzymes begin to denature, meaning that their protein structures change. The shape of the active site changes and they can no longer collide with the right substrate, as it doesn't fit in the active site.

Figure 1