Correct Answer: C

Rationale: The correct answer is C: mucus. Mucus forms a protective barrier that prevents the stomach and intestine from digesting themselves. Pepsinogen (choice A) is an inactive form of pepsin, a digestive enzyme, and does not protect the stomach lining. Bile (choice B) aids in the digestion and absorption of fats but does not protect the stomach lining. Fat (choice D) is a nutrient and energy source; it does not play a role in protecting the stomach and intestine from self-digestion.

Correct Answer: A

Rationale: Cholecystokinin (CCK) is produced in the duodenum, not the stomach, pancreas, or liver. It is released in response to the presence of food in the duodenum, where it plays a crucial role in regulating digestive processes by stimulating the release of bile from the gallbladder and enzymes from the pancreas. Therefore, the correct answer is the duodenum (Choice A). Choices B, C, and D are incorrect because CCK is not produced in the stomach, pancreas, or liver.

Correct Answer: B

Rationale: The correct answer is B: Glycogenolysis. Glycogenolysis is the process of breaking down glycogen into glucose. Choices A, C, and D are incorrect. Glucogenesis (choice A) is not a term used in biochemistry. Glyconeogenesis (choice C) refers to the synthesis of new glucose molecules from non-carbohydrate sources, not the breakdown of glycogen. Gluconeogenesis (choice D) is the process of producing glucose from non-carbohydrate sources, not the breakdown of glycogen.

Correct Answer: D

Rationale: The correct answer is D: gastroesophageal reflux disease (GERD). GERD occurs when stomach acid flows back into the esophagus, causing symptoms like heartburn and regurgitation. Choice A, hiatal hernia, is a condition where part of the stomach pushes up into the chest through an opening in the diaphragm. Choice B, diverticulitis, is inflammation or infection of small pouches that can form in the lining of the digestive system. Choice C, gastroenteritis, is inflammation of the stomach and intestines typically caused by a viral or bacterial infection. Therefore, only choice D accurately describes the regurgitation or reflux of acidic stomach contents back into the esophagus.

Correct Answer: A

Rationale: Glucose serves as a primary source of energy for the body, especially for the brain and muscles. Choice B is incorrect because glucose itself is not responsible for transporting oxygen to cells. Choice C is incorrect as glucose is converted to glycogen, not the other way around. Choice D is incorrect as glucose itself does not play a direct role in maintaining body weight.