Explain using the lock-and-key model why pepsin can hydrolyze peptide bonds in proteins but not the glycosidic bonds in starch.

• A. Pepsin lacks the necessary cofactors to hydrolyze glycosidic bonds in starch.
• B. Pepsin's active site is specifically shaped to bind to peptide bonds in proteins.
• C. Pepsin's active site matches the structure of starch.
• D. Pepsin is only active in an acidic environment.

Answer: (B)