Correct Answer: B

Rationale: The correct answer is B: Plant sterols. Plant sterols can reduce cholesterol absorption by competing with cholesterol for absorption sites. Vitamin K, choice A, does not have a significant impact on cholesterol absorption. Trans fats, choice C, are known to increase cholesterol levels rather than decrease absorption. Phospholipids, choice D, play a role in cell structure and are not directly involved in reducing cholesterol absorption.

Correct Answer: D

Rationale: The correct term for a vegetarian diet that includes both dairy foods and eggs is 'ovolactovegetarian.' This term specifically indicates the inclusion of eggs ('ovo') and dairy ('lacto') in the diet. Choice A, 'lactovegetarian,' is incorrect because it only includes dairy products without eggs. Choice B, 'vegan,' is incorrect as it excludes all animal products, including dairy and eggs. Choice C, 'semi-vegetarian,' is incorrect as it is a term used for individuals who occasionally eat meat, poultry, or fish but primarily follow a plant-based diet.

Correct Answer: B

Rationale: Carbohydrates have a protein-sparing effect, meaning that adequate carbohydrate intake can prevent the use of protein for energy. Glycerol, nitrogen, and fatty acids do not have a protein-sparing effect. Glycerol is a component of fats and oils, nitrogen is a component of proteins, and fatty acids are used primarily as an energy source.

Correct Answer: B

Rationale: Pepsinogen is converted into its active form, pepsin, by hydrochloric acid in the stomach. Hydrochloric acid helps in unfolding the pepsinogen molecule to transform it into pepsin, which is crucial for protein digestion. Therefore, the correct answer is hydrochloric acid (choice B). Enterokinase (choice A) is an enzyme produced in the small intestine that activates trypsinogen into trypsin, not pepsinogen. Gastric lipase (choice C) is an enzyme that digests fats, not involved in converting pepsinogen to pepsin. Pancreatic lipase (choice D) is an enzyme produced by the pancreas that aids in breaking down fats in the small intestine, not part of the process of pepsin activation.

Correct Answer: C

Rationale: The correct answer is C: amino acids. Proteins are broken down by digestive enzymes into amino acids before being absorbed in the small intestine. Amino acids are the building blocks of proteins and are the form in which they are primarily absorbed. Choice A (fatty acids) is incorrect as fatty acids are the end products of fat digestion, not protein digestion. Choice B (disaccharides) is incorrect because disaccharides are sugars that are broken down into monosaccharides, not proteins. Choice D (polypeptides) is incorrect as proteins are broken down into amino acids and not absorbed as polypeptides.