What is the main purpose of digestion?

• A. To break down food into smaller molecules that can pass through the cell membrane
• B. To emulsify fats in the stomach
• C. To break down proteins into amino acids
• D. To absorb water in the colon

Answer: (A)

The purpose of digestion is to break down large, complex food molecules into smaller, soluble units that can cross the intestinal lining and enter the bloodstream to be used by body cells. This conversion makes nutrients available for energy, growth, and repair. Emulsifying fats in the gut helps digestion by increasing surface area for enzymes, but it isn’t the overall goal of digestion. Breaking down proteins into amino acids is important, but digestion aims to produce a range of absorbable monomers from all macromolecules, not just proteins. Absorbing water in the colon happens after digestion, as part of processing waste, not during digestion itself.