Final answer:
Starch digestion starts in the mouth, protein digestion begins in the stomach using pepsin and HCl, and protein digestion completes in the small intestine.
Step-by-step explanation:
Starch digestion begins in the mouth where salivary amylase breaks down the starch into smaller carbohydrates. The process of protein digestion initiates in the stomach, where hydrochloric acid (HCl) denatures proteins, and the enzyme pepsin begins breaking them down into smaller peptides. As digestion continues, protein digestion is completed in the small intestine, where pancreatic juices contain enzymes like trypsin and chymotrypsin further break down these peptides that is into amino acids.
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