Which effect does a gradual decrease in pH from 13 to 1 have on the action of amylase?

A decrease in pH is too acidic compared to optimum pH for amylase activity. The hydrogen ion changes amylase sites of activity and amylase activity become low. At pH 13 to 1 which is acidic, reduces the activity of amylase because the hydrogen ion changes amylase activity sites and render it's action low which will denatures amylase and make it ineffective.

Explanation:

Amylase refer to enzymes that catalyses or breakdown starch into sugars. General, enzymes are biological substances that speed up the rate of chemical reactions.

Enzymes generally are affected by pH. The most favorable pH is the optimum pH which make amylase to be effective or enzymes.

A high pH or low pH has effect on the enzymes and will reduces enzymes activities. A low pH will cause the hydrogen ion to alter the enzymes sites and reduce their activities while high pH will cause the hydroxides ion to alter the enzymes activity sites.