Question

Which organ secretes enzymes that are active at a low pH?

Answer 1

The stomach

Explanation:

The stomach is the only organ in the body that has a very low pH (acidic), as can be seen in the image below. This is where the digestion of proteins from food starts.

To break down proteins, the stomach produces the enzyme pepsin that works best at pH 2.5.

To be more precise, the stomach produces a precursor of this enzyme called pepsinogen. The stomach also produces hydrochloric acid which activates pepsinogen forming the functional enzyme pepsin.