Correct Answer: B

Rationale: The correct answer is B: 7 kcal/g. Alcohol provides approximately 7 kilocalories per gram, making it a significant source of energy or 'empty calories' in the diet that do not contain any nutrients. 'Empty calories' refer to the calorie content without the presence of essential nutrients. Choices A, C, and D are incorrect. The energy values of 3 kcal/g, 10 kcal/g, and 25 kcal/g are not accurate for alcohol; instead, they may pertain to other nutrients such as carbohydrates (approximately 4 kcal/g), fats (approximately 9 kcal/g), and oils (approximately 9 kcal/g).

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: C

Rationale: Option C is correct because a food frequency questionnaire is designed to capture a person's typical food intake over an extended period and is not suitable for monitoring short-term changes in diet. The questionnaire's purpose is to provide insights into long-term dietary patterns rather than immediate changes. Option A is incorrect as the questionnaire does not influence food choices; it merely records them. Option B is also incorrect because, while seasonal changes can impact food availability and thereby influence diet, the questionnaire itself is not affected by these changes. Lastly, option D is incorrect as the time to obtain results from a food frequency questionnaire would depend on the respondent's speed and accuracy rather than being intrinsically linked to the questionnaire.

Correct Answer: B

Rationale: The correct answer is B, galactose. Galactose naturally occurs in foods only when it is combined with glucose to form lactose, a disaccharide found in milk. Fructose is a monosaccharide found in fruits and honey. Sucrose is a disaccharide composed of glucose and fructose, commonly known as table sugar. Maltose is a disaccharide formed by the combination of two glucose molecules.

Correct Answer: A

Rationale: Carbohydrates are composed of carbon, hydrogen, and oxygen. These three elements combine to form the basic structure of carbohydrates. Oxygen is an essential element in carbohydrates, contributing to their chemical composition. Choice B (nitrogen) is incorrect as nitrogen is not a typical component of carbohydrates. Choice C (water) is incorrect as water is not an element but a compound composed of hydrogen and oxygen. Choice D (glucose) is incorrect as glucose is a specific type of sugar, not an element found in the composition of carbohydrates.