False, I believe. Mutations sometimes might have an effect that helps the population. Example: I've heard of Two-Headed snakes, and even seen some on the internet. They live their lives just fine, so I suppose the mutation was actually quite helpful.
The factor that may influence enzymes activity are------ 1) temperature - increasing temperature increases the kinetic energy. 2) concentration- changing the enzyme substrate concentration effect the rate of reaction of an enzyme catalysed reaction.