Correct Answer: C

Rationale: The correct answer is 'health care agent.' A health care agent is appointed through a durable power of attorney to make medical decisions on behalf of a patient who becomes incapacitated. The term 'witness' (choice A) is incorrect because a witness only observes the signing of the directive and does not make decisions. 'Primary caregiver' (choice B) is also incorrect as they may provide care but are not necessarily legally empowered to make decisions. 'State proxy' (choice D) is not commonly used in the context of advance directives or health care decision making, making it an incorrect choice.

Correct Answer: D

Rationale: Option A is correct because lipoproteins indeed transport lipids in the blood. They are complexes of lipids and proteins that transport water-insoluble lipids through the blood. Option B is correct as it accurately describes the condition of type II diabetes where the pancreas can produce insulin, but the cells are resistant to its signal, causing an ineffective regulation of blood sugar. Option C is also correct because the glycemic index is indeed a classification system for foods based on their potential to raise blood glucose levels. High glycemic index foods raise blood glucose levels faster than low glycemic index foods. Hence, all the statements are correct, making option D the correct answer.

Correct Answer: B

Rationale: The correct answer is B. The classification of the 20 common amino acids is not based on the properties of their side chains, but rather on the structure of their amino and carboxyl groups. These groups are consistent among all amino acids, while the side chains, also known as R groups, are what vary and give each amino acid its unique properties. Choice A is correct because proteins are indeed composed of amino acids. Choice C is incorrect because while the side chains of amino acids can vary, the general structure of an amino acid - a central carbon atom bonded to an amino group, a carboxyl group, a hydrogen atom, and a side chain - is consistent. Choice D is correct because amino acids do polymerize to form long chains called polypeptides, which can then fold into complex shapes to form proteins.

Correct Answer: A

Rationale: Essential fatty acids play a crucial role in improving skin integrity by supporting the structure and function of cell membranes. This helps in maintaining healthy skin and promoting overall well-being. The other choices are incorrect because essential fatty acids do not directly control lipid digestion, reduce blood clotting time, or form chylomicrons.

Correct Answer: C

Rationale: Lipase is an enzyme that specifically breaks down lipids (fats) during the process of digestion, converting them into fatty acids and glycerol. This is why option C is the correct answer. Although option D is partially correct, it's less specific than option C. Lipase does not break down carbohydrates or proteins, so options A and B are incorrect.