Protein digesting enzyme pepsin is secreted in . . . . . . part of the digestive system.

Identify the enzymes at $A$ and $B$ which hydrolyze the substrates.
Proteins $\xrightarrow{ A }$ $\begin{array}{c}\text{peptones} \\ + \\ \text{proteoses}\end{array}$ $\xrightarrow{ B }$ polypeptides

Rennin acts on milk proteins and converts

How is the intestinal mucosa protected from the acidic food entering from the stomach?

The proteolytic enzyme found in the gastric juice of infants which helps in the digestion of milk proteins is

Which $pH$ value is optimal for the action of enzymes on food in the stomach?