Starch is digested to maltose by the enzyme amylase. According to the 'lock and key' hypothesis, which is the 'key' and which is the 'lock'?

Correct Answer: A

Rationale: In the lock and key model, the enzyme (amylase) is the key that specifically binds to the substrate (starch), acting as the lock.

Correct Answer: D

Rationale: Sebum is an oily substance produced by sebaceous glands in the skin, not by gastric glands, which secrete HCl, intrinsic factor, and pepsin.

Correct Answer: A

Rationale: The liver consists of lobules, functional units where hepatocytes radiate from a central vein, facilitating its metabolic roles.

Correct Answer: B

Rationale: Peristalsis involves coordinated muscle contractions to push food forward.

Correct Answer: B

Rationale: The superior surface of the soft palate is covered by pseudostratified ciliated columnar epithelium (respiratory epithelium), not stratified columnar, due to its proximity to the nasopharynx.