The correct option is Trypsin.
Explanation
Digestion involves the chemical breakdown of food into absorbable nutrients through the action of enzymes. Proteolytic enzymes (proteases) specifically catalyze the hydrolysis of proteins into peptides and amino acids. These enzymes are secreted by various organs, including the stomach and pancreas, and require specific pH environments to function effectively.
Option Analysis
- Trypsin is correct: Trypsin is a major proteolytic enzyme secreted by the pancreas in an inactive form known as trypsinogen. It is released into the duodenum (part of the small intestine) via the pancreatic duct. In the small intestine, it is activated by enterokinase and acts to break down proteins in an alkaline environment.
- Pepsin is incorrect: Pepsin is a proteolytic enzyme secreted by the gastric glands of the stomach. It functions in the acidic environment of the stomach to initiate protein digestion, rather than in the small intestine.
- Lactase is incorrect: Lactase is an enzyme responsible for breaking down lactose (milk sugar), making it a carbohydrase, not a proteolytic enzyme. Furthermore, it is secreted by the brush border of the small intestine, not the pancreas.
- Invertase is incorrect: Invertase (sucrase) catalyzes the hydrolysis of sucrose (cane sugar) into glucose and fructose. It acts on carbohydrates and is typically associated with the intestinal brush border or plant physiology, not pancreatic protein digestion.
Key Takeaway: Trypsin is the primary pancreatic enzyme responsible for protein digestion within the small intestine, distinguishing it from gastric pepsin and intestinal carbohydrases.