Which one of the following pairs of enzymes do not work at acidic pH?

Enzymatic activity is highly dependent on pH levels. Pepsin is a gastric enzyme that functions optimally in the highly acidic environment of the stomach, typically at a pH of 1.5 to 2 [3]. In contrast, enzymes like trypsin and amylase do not work at acidic pH. Trypsin is a pancreatic protease that operates in the small intestine, where the environment is made alkaline by bile and pancreatic secretions to reach an optimal pH of approximately 8 [2]. Similarly, salivary and pancreatic amylase function best in neutral to slightly alkaline conditions, with an optimal pH range of 6.7 to 7.0 [4]. While pepsin becomes inactive as the pH rises above 6 in the duodenum, trypsin and amylase lose their activity or fail to function effectively in the acidic conditions characteristic of the stomach [3]. Therefore, the pair that does not work at acidic pH is trypsin and amylase.

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/NBK537005/
3. [2] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Activity 5.3 > p. 86
4. [4] https://www.ncbi.nlm.nih.gov/books/NBK544242/