Regarding calcium:

Correct Answer: C

Rationale: The correct answer is C because 1,25-dihydroxycholecalciferol, the active form of vitamin D, does induce calcium binding protein synthesis in mucosal cells, facilitating calcium absorption. This process occurs in the small intestine. Choices A and B are incorrect because around 30% of calcium is typically absorbed, and active transport of Ca2+ primarily occurs in the upper small intestine. Choice D is incorrect because phosphate does not directly facilitate calcium absorption.

Correct Answer: C

Rationale: The correct answer is C: Larynx. The alimentary canal is the digestive tract where food passes through. The larynx is not part of this pathway; it is part of the respiratory system, specifically involved in phonation and protecting the trachea during swallowing. The mouth, pharynx, and esophagus are all part of the alimentary canal, where food is ingested, swallowed, and transported to the stomach for digestion. Therefore, the larynx is the correct answer as it is not part of the digestive process.

Correct Answer: B

Rationale: The correct answer is B: To digest carbohydrates. The stomach primarily digests proteins through the action of pepsin and hydrochloric acid. Carbohydrates are primarily broken down in the mouth by salivary amylase, not in the stomach. Choices A, C, and D are incorrect because the stomach does play a role in digesting proteins, temporarily storing food, and neutralizing alkali from the mouth, respectively.

Correct Answer: D

Rationale: The correct answer is D because hormones are released into the bloodstream by endocrine glands and travel to specific target tissues, where they bind to receptors on the surface or within the cells. This binding triggers a series of cellular responses that regulate various physiological processes. Choices A, B, and C are incorrect because hormones do not affect target tissues through the digestive system, nervous system, or by secreting mucus. Hormones act specifically by binding to receptors on target cells to initiate their effects.

Correct Answer: C

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.