Why are pancreatic proteases secreted as inactive zymogens?

• A. To ensure pancreatic enzymes are active in the stomach.
• B. To allow digestion to start in the mouth.
• C. To maximize enzyme activity in the pancreas before secretion.
• D. To prevent autodigestion of pancreatic tissue; activation occurs in the small intestine.

Answer: (D)

The key idea is to stop the pancreas from digesting itself. Pancreatic proteases are released as inactive forms called zymogens so they don’t start breaking down pancreatic tissue while stored or before they reach the digestive tract. Activation is then tightly controlled in the small intestine: an enzyme in the intestinal lining, enterpeptidase, converts trypsinogen into active trypsin, and trypsin then activates the other proteases. This staged activation ensures that proteolytic activity happens only where it’s needed—in the small intestine after neutralizing stomach acid and mixing with food—rather than inside the pancreas. So the correct reasoning is that zymogens prevent autodigestion of pancreatic tissue, with activation occurring later in the small intestine.