Lock and Key Model in Enzyme Action

Steps:

• Recall the lock and key model: the enzyme's active site (lock) fits the substrate (key) precisely for reaction.
• Identify the enzyme: lipase, which catalyzes the breakdown.
• Identify the substrate: fats, the molecule being broken down.
• Match to model: enzyme as lock, substrate as key.

Why B is correct:

• In the lock and key model, the enzyme (lipase) is the lock with a specific active site shape, and the substrate (fats) is the key that fits it to form the enzyme-substrate complex.

Why the others are wrong:

• A: Reverses roles; substrate is key, not enzyme.
• C: Fatty acids and glycerol are products, not the key (substrate).
• D: Fatty acids and glycerol are products, not the key.

Final answer: B