Final answer:
Bicarbonate ions are not found in pancreatic secretions. They help neutralize the acidic chyme and create a favorable environment for digestion in the small intestine.
Step-by-step explanation:
Bicarbonate ions are found in pancreatic secretions, so they are NOT the correct answer to the given question. Procarboxypeptidase, cholecystokinin (CCK), and chymotrypsinogen, on the other hand, are all found in pancreatic secretions and are part of the digestive process. Bicarbonate ions are important because they help neutralize the acidic chyme produced in the stomach, creating a more favorable environment for the digestive enzymes to function in the small intestine.