What effect does extreme temperature and extreme ph have on enzyme activity?

it speeds up enzyme activity.
it slows down enzyme activity.
it stops enzyme activity.
it has no effect on enzyme activity.

small, big, or no change could occur in the phenotype. it could cause something as simple as a cats ears to curl backwards or something as frighting as death. it could also occur in the protien-coding area and have an effect on that but no effect on the amino acids. what has to occur is a changing in the hox gene or the control gene.