Which is a true statement about enzyme activity ph and enzyme action?

a. all enzymes work best at a neutral ph

b. adding more acid does not affect the rate of activity of an enzyme

c. enzymes function only in a ph range of 4.0 to 5.5

d. the activity of an enzyme is affected by ph

answer must be D. A, B and C cannot be true as different enzymes have different optimum pH. For instance the enzyme pepsin in the stomach works best at pH 2 , the enzyme trypsin works best at pH 8 while amylase works best at pH 7.

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.

cell division is not regulated in tumor cells.