Why is digestion necessary?

• A. For storage
• B. For absorption
• C. For transport
• D. For excretion

Answer: (B)

Digestion is necessary because the nutrients in food are too large to cross the gut lining in their original form. Through both mechanical and chemical processes, food is broken down into small, soluble molecules—carbohydrates into sugars, proteins into amino acids, fats into fatty acids and glycerol. These smaller molecules can then be absorbed by the cells lining the small intestine and enter the bloodstream or lymphatic system to be used for energy, growth, and repair throughout the body. Without this breakdown, nutrients wouldn’t be absorbed efficiently and the body's cells wouldn’t receive the fuel they need. After absorption, nutrients are transported, stored, or excreted as part of other bodily processes, but digestion’s main role is enabling absorption.