Correct Answer: D

Rationale: Chylomicrons are particles that transport dietary fats from the small intestine to cells in the body. They are cleared from the bloodstream by lipoprotein lipase, an enzyme that breaks down triglycerides in chylomicrons into fatty acids and glycerol. This process allows fats to be absorbed by the body. Choices A, B, and C are incorrect because chylomicrons are not formed in the hepatic system, they are composed of various lipids including triglycerides and cholesterol, and they are absorbed in the small intestine, not the large intestine.

Correct Answer: D

Rationale: The correct answer is D: 20. There are 20 different amino acids that combine to form proteins in the human body. Each amino acid has a unique side chain that determines its properties. Choices A, B, and C are incorrect as they do not represent the total number of different amino acids found in human proteins.

Correct Answer: B

Rationale: The correct answer is B: chyme. Chyme is the partially digested food that forms a semifluid mass after mixing with gastric juices. A is incorrect because a bolus refers to a rounded mass of food ready to be swallowed. C, rennin, is an enzyme involved in the digestion of milk proteins and not the term for the semifluid mass after food mixing with gastric secretions. D, glycogen, is a form of stored glucose in the body and is not the term used to describe the partially digested food mass in the stomach.

Correct Answer: D

Rationale: The correct answer is D: Absorption of water. The primary nutritional function of the large intestine is to absorb water from the indigestible food residue that enters it from the small intestine. This absorption of water helps to form solid waste, which is then eliminated from the body. Choices A, B, and C are incorrect because the large intestine is not primarily responsible for the absorption of fats, excretion of waste products, or excretion of bacteria. While the large intestine does play a role in waste elimination and contains bacteria beneficial for digestion, its main function in terms of nutrition is the absorption of water.

Correct Answer: B

Rationale: The correct answer is B: Presence of fat in the duodenum. Cholecystokinin (CCK) is released in response to the presence of fat in the duodenum to aid in digestion by stimulating the release of bile from the gallbladder and enzymes from the pancreas. Options A, C, and D are incorrect because CCK is specifically released in response to the presence of fat in the duodenum, not food in the stomach, acid chyme in the ileum, or bile in the gallbladder.