How is the stomach protected from damage by gastric acid?

Correct Answer: D

Rationale: The correct answer is D. The stomach is protected from gastric acid by a thick mucus lining that acts as a physical barrier, preventing the acid from eroding the stomach walls. Enzymes in the stomach help with digestion but do not play a significant role in protecting the stomach from acid damage, so choice A is incorrect. While some bacteria in the stomach can be beneficial, they do not primarily protect the stomach from gastric acid, making choice B incorrect. Bicarbonate, a base, can neutralize acid, but it is not the primary defense mechanism against gastric acid in the stomach, so choice C is also incorrect.

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 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.