Q.Explain the following :
Cooking makes food easy to digest.

Step 1. What raw food is, chemically. Section 16.1 describes most nutrients as large organic macromolecules -- proteins and carbohydrates specifically being polymers -- and raw, uncooked food as a heterogeneous suspension of these.

Step 2. What cooking does to it. During cooking, the high polymers of carbohydrate or protein are hydrolysed into smaller polymer fragments, and the mixture's physical character changes from a heterogeneous suspension to a colloidal system.

Step 3. Why smaller/colloidal means easier digestion. Digestion itself works by enzymes further breaking these polymers down into monomers (amino acids from protein, glucose from carbohydrate) -- starting from already-smaller, already-colloidal cooked food gives the digestive enzymes less work to do and a more accessible substrate than the larger, less accessible molecules in a raw heterogeneous suspension.

Explaining the polymer-hydrolysis and suspension-to-colloid change described in Section 16.1

• Saying cooking 'just kills bacteria', which misses the actual chemical reason (polymer breakdown, colloid formation) the chapter gives for easier digestion.
• Reversing cause and effect -- digestion breaks polymers into monomers; cooking only partially pre-breaks them into smaller polymers, it does not complete digestion itself.