Question

Difficulty: MediumHuman Physiology, Health, and Diseases

Match the human digestive enzymes listed in List-I with their primary physiological functions and sites of action listed in List-II:

  • PepsinInitiates protein digestion in the highly acidic environment of the stomach
  • TrypsinCleaves proteins into smaller peptides in the alkaline environment of the small intestine
  • AmylaseHydrolyzes starch and complex carbohydrates into disaccharides and simple sugars
  • LipaseBreaks down dietary lipids and triglycerides into free fatty acids and glycerol

Answer

Pepsin matches with initiating protein digestion in the acidic stomach environment; Trypsin matches with cleaving proteins into peptides in the alkaline intestinal environment; Amylase matches with hydrolyzing starch into simple sugars; and Lipase matches with breaking down lipids into fatty acids and glycerol.
Each enzyme is paired correctly based on its substrate and site of physiological action: Pepsin initiates protein digestion in the stomach under acidic conditions; Trypsin continues protein digestion in the small intestine under alkaline conditions; Amylase breaks down complex starches into sugars; and Lipase hydrolyzes fats into fatty acids and glycerol.

Step-by-Step Solution

1
Identify gastric protein-digesting enzymes and their optimal environment.
Pepsin operates in the acidic gastric juice (pH ~1.5–2.0) of the stomach to digest proteins into peptones.
Hydrochloric acid secreted by parietal cells activates pepsinogen into pepsin.
2
Identify intestinal protein-digesting enzymes and their optimal environment.
Trypsin acts in the duodenum/small intestine where pancreatic bicarbonate creates an alkaline pH (~7.5–8.0).
Pancreatic proteases require neutral to slightly alkaline conditions for optimal enzymatic activity.
3
Map carbohydrate and lipid degrading enzymes to their specific substrate reactions.
Amylase acts on carbohydrates (starches), while Lipase acts on lipids (fats).
Enzyme specificity dictates that amylase breaks down α-1,4-glycosidic bonds, whereas lipase hydrolyzes lipid ester bonds.

Key Concept

Human Digestive Enzymes, Substrate Specificity, and pH Requirements
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