Correct Answer: B

Rationale: It is false that the major determinant of a person's total cholesterol levels is the amount of cholesterol in their diet. While dietary cholesterol can have some impact on total cholesterol levels, it is not the major determinant. The amount and types of fats consumed, particularly saturated and trans fats, have a more significant impact on blood cholesterol levels. Therefore, a diet high in these types of fats can lead to high cholesterol, irrespective of the amount of dietary cholesterol consumed. This is why it is essential to maintain a balanced diet with a limited intake of saturated and trans fats.

Correct Answer: D

Rationale: The correct answer is D: 'Consume orange juice as a beverage with a meal'. This is because Vitamin C significantly enhances the absorption of non-heme iron, a form of iron found in plant-based foods. Therefore, consuming orange juice, which is rich in vitamin C, with a meal can effectively increase iron absorption. On the contrary, choices A, B, and C are incorrect. Coffee (Choice A) contains polyphenols that can inhibit iron absorption. Avoiding vitamin C-rich foods (Choice B) would decrease iron absorption, not increase it. While calcium (Choice C) is essential for many bodily processes, it can actually inhibit iron absorption when consumed together.

Correct Answer: C

Rationale: One pound of body fat is equivalent to approximately 3500 calories. This is a generally accepted caloric value used in nutrition and weight management. It's important to note that this is an estimation and individual variations may occur. Choice A (1500 calories), Choice B (2500 calories), and Choice D (5000 calories) are incorrect because they do not match the generally accepted caloric value of 3500 calories for one pound of body fat.

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: Protein catabolism increases in conditions like severe burns because the body breaks down muscle protein to provide energy for healing. Severe obesity does not necessarily increase protein catabolism; instead, it is more related to excessive fat accumulation. Hypothyroidism may lead to a decrease in metabolic rate but does not directly increase protein catabolism. Food allergies trigger an immune response to specific foods but do not directly impact protein catabolism.