Matching digestive organ functions to labeled parts

Steps:

• Label 1 as stomach, which secretes pepsin for protein digestion into peptides and amino acids.
• Label 3 as small intestine, where villi absorb digested products like amino acids, glucose, and fatty acids.
• Evaluate options: A aligns with stomach protein breakdown and small intestine absorption roles.
• Eliminate mismatches in B, C, D based on incorrect organ functions like fat emulsification or enzyme storage.

Why A is correct:

• Stomach (1) uses hydrochloric acid and pepsin to initiate protein digestion, while small intestine (3) absorbs the resulting soluble products via microvilli.

Why the others are wrong:

• B: Pancreas (2) secretes lipase for fat digestion, but bile (not from 2) emulsifies fats.
• C: Liver (4) produces bile, but pancreas (5, if labeled) makes enzymes; gall bladder stores bile.
• D: Liver (4) neither stores nor produces digestive enzymes; pancreas (2) produces them.

Final answer: A