Where does carbohydrate digestion begin?

Correct Answer: A

Rationale: Carbohydrate digestion begins in the mouth. The enzyme amylase, found in saliva, starts the process by breaking down starches into sugars. The esophagus is a passageway for food to reach the stomach and does not participate in digestion. The stomach mainly digests proteins and is not the primary site for carbohydrate breakdown. While the small intestine does play a crucial role in digesting carbohydrates, it is not where the process initiates. Therefore, the correct answer is the mouth.

Correct Answer: D

Rationale: The Dietary Reference Intake (DRI) for protein is primarily determined by an individual's body weight. This is because the body's protein requirement is proportionate to its size, which is generally reflected in the body weight. Therefore, choice D is correct. Choices A, B, and C are incorrect: While factors such as fatty acid intake, gender, and height can influence an individual's overall nutritional needs, they do not directly determine the DRI for protein.

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: A

Rationale: The correct answer is A: vitamin B12. Intrinsic factor is a glycoprotein produced by the stomach that is necessary for the absorption of vitamin B12 in the small intestine. Vitamin B12 binds to intrinsic factor in the stomach, forming a complex that is then absorbed in the ileum. This absorption process is crucial for preventing vitamin B12 deficiency. Choices B, C, and D are incorrect because they do not require intrinsic factor for absorption. Folate is absorbed in the small intestine through a different mechanism, niacin can be absorbed in the small intestine without the need for intrinsic factor, and vitamin B6 does not rely on intrinsic factor for absorption.

Correct Answer: D

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.