If by an unknown accident the acid secreting cells of the stomach wall of an individual are damaged, digestion of which one of the following biomolecule will be affected to a greater extent ?

The stomach's parietal cells secrete hydrochloric acid (HCl), which is essential for creating an acidic environment (pH 1.5 to 2.5) [1]. This low pH is critical for the activation of pepsinogen, an inactive zymogen secreted by chief cells, into the active proteolytic enzyme pepsin. Pepsin is the primary enzyme responsible for initiating the chemical digestion of proteins in the stomach [1]. While the stomach also secretes gastric lipase for lipid digestion, its activity is less significant compared to pancreatic lipase in the small intestine [3]. Carbohydrate digestion begins in the mouth with salivary amylase and is completed in the small intestine by pancreatic enzymes [3]. Therefore, if acid-secreting cells are damaged, the failure to activate pepsin will disproportionately affect the digestion of proteins.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Activity 5.3 > p. 85
2. [3] https://www.ncbi.nlm.nih.gov/books/NBK544242/