In a given tooth, the dentin is located ______ to the enamel.

Correct Answer: A

Rationale: The correct answer is A: inferior. Dentin is located beneath the enamel in a tooth, making it inferior to the enamel. Enamel is the outermost layer of the tooth that covers the dentin. Therefore, the dentin is positioned below or inferior to the enamel. Choice B (anterior) refers to the front of a tooth, not its relationship to dentin. Choice C (superior) means above, which is not correct in this context. Choice D (posterior) refers to the back of a tooth, not its position relative to the enamel.

Correct Answer: B

Rationale: The correct answer is B: ileum. The ileum is the longest region of the small intestine, measuring about 6-7 meters in length. It is responsible for further digestion and absorption of nutrients, particularly vitamin B12 and bile salts. The duodenum is the first part of the small intestine and is relatively short, the jejunum is the middle section of the small intestine, and the colon is part of the large intestine. Therefore, the ileum is the correct answer based on its length and function in the digestive process.

Correct Answer: D

Rationale: The correct answer is D, cholecystokinin. Cholecystokinin is released in response to the presence of fatty acids and amino acids in the duodenum, stimulating the secretion of the enzymatic component of pancreatic juice. Gastric inhibitory polypeptide (A) regulates insulin release, not pancreatic enzyme secretion. Secretin (B) stimulates bicarbonate secretion from the pancreas, not enzyme secretion. Gastrin (C) stimulates gastric acid secretion, not pancreatic enzyme secretion. Therefore, cholecystokinin is the correct hormone for stimulating the enzymatic component of pancreatic juice secretion.

Correct Answer: A

Rationale: The correct answer is A: stomach and pancreas. Firstly, protein digestion starts in the stomach where pepsinogen is converted to pepsin, breaking down proteins. Secondly, the pancreas secretes enzymes like trypsin and chymotrypsin into the small intestine to further break down proteins. The other choices are incorrect because the salivary glands primarily produce enzymes for carbohydrate digestion, while the small intestine is more involved in absorbing nutrients rather than producing protein-digesting enzymes.

Correct Answer: B

Rationale: The correct answer is B: Bile salts emulsify fat, aiding in fat digestion. Bile salts are amphipathic molecules that break down large fat globules into smaller droplets, increasing the surface area for enzymes to act upon. This enhances fat digestion and absorption. Choice A is incorrect because pepsinogen conversion is not a function of bile salts. Choice C is incorrect as bile salts are essential for digestion. Choice D is incorrect as bile salts specifically target fats, not all macromolecules.