Which pathogenic bacterium is associated with peptic ulcer disease and gastric cancer?

Correct Answer: C

Rationale: The correct answer is H. pylori. This bacterium is known to be associated with the development of peptic ulcers and an increased risk of gastric cancer. Lactobacillus (Choice A) and Bifidobacterium (Choice B) are probiotic bacteria that are beneficial to human health and not associated with causing these conditions. E. coli (Choice D) is a diverse group of bacteria, some of which can be pathogenic, but they are not primarily linked to peptic ulcers and gastric cancer like H. pylori.

Correct Answer: D

Rationale: The correct answer is D: portal blood system. After absorption, carbohydrates and proteins are transported via the portal blood system to the liver for further processing and distribution to the rest of the body. Choices A, B, and C are incorrect. Enterohepatic circulation refers to the recycling of compounds between the liver and the intestines, not the direct route for absorbed nutrients. Gastrointestinal circulation is a vague and non-specific term, not specifically related to the transport of absorbed nutrients. The common bile duct is involved in transporting bile from the liver and gallbladder to the small intestine, not the end products of carbohydrate and protein digestion.

Correct Answer: D

Rationale: Chylomicrons are particles that transport dietary fats from the small intestine to cells in the body. They are cleared from the bloodstream by lipoprotein lipase, an enzyme that breaks down triglycerides in chylomicrons into fatty acids and glycerol. This process allows fats to be absorbed by the body. Choices A, B, and C are incorrect because chylomicrons are not formed in the hepatic system, they are composed of various lipids including triglycerides and cholesterol, and they are absorbed in the small intestine, not the large intestine.

Correct Answer: D

Rationale: The correct answer is D: Absorption of water. The primary nutritional function of the large intestine is to absorb water from the indigestible food residue that enters it from the small intestine. This absorption of water helps to form solid waste, which is then eliminated from the body. Choices A, B, and C are incorrect because the large intestine is not primarily responsible for the absorption of fats, excretion of waste products, or excretion of bacteria. While the large intestine does play a role in waste elimination and contains bacteria beneficial for digestion, its main function in terms of nutrition is the absorption of water.

Correct Answer: A

Rationale: The correct answer is A: ileocecal valve. The ileocecal valve is located between the small intestine and the cecum, controlling the passage of chyme. The pyloric valve (choice B) is located between the stomach and the small intestine, regulating the passage of food from the stomach to the small intestine. The cardiac valve (choice C) refers to the valve between the esophagus and the stomach. The hepatic valve (choice D) is not a correct term related to the passage of chyme from the small intestine into the cecum.