Nokea
What triggers the release of cholecystokinin (CCK)?
- A. Presence of food in the stomach.
- B. Presence of fat in the duodenum.
- C. Entry of acid chyme into the ileum.
- D. Entry of bile into the gallbladder.
Correct Answer: B
Rationale: The correct answer is B: Presence of fat in the duodenum. Cholecystokinin (CCK) is released in response to the presence of fat in the duodenum to aid in digestion by stimulating the release of bile from the gallbladder and enzymes from the pancreas. Options A, C, and D are incorrect because CCK is specifically released in response to the presence of fat in the duodenum, not food in the stomach, acid chyme in the ileum, or bile in the gallbladder.
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What is the function of chylomicrons?
- A. Produced in the hepatic system.
- B. Composed of triglycerides and cholesterol only.
- C. Absorbed in the large intestine.
- D. Cleared from the blood by lipoprotein lipase.
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.
The lining of the stomach and intestine is protected from self-digestion by:
- A. pepsinogen.
- B. bile.
- C. mucus.
- D. fat.
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.
What is the chemical structure that forms the base component of an amino acid?
- A. carboxyl group
- B. carbon chain
- C. radicals
- D. amino group
Correct Answer: D
Rationale: The correct answer is the amino group. Amino acids consist of an amino group (NH2), a carboxyl group (COOH), a hydrogen atom, and a variable side chain attached to a central carbon atom. The amino group is essential for the formation of proteins. The carboxyl group is not the base component but another important functional group in amino acids. Carbon chain and radicals are not specific chemical structures that form the base component of an amino acid.
At what pH does the digestion of protein by pepsin in the stomach require?
- A. 1.8 and 3.5.
- B. 4.8 and 7.0.
- C. 6.8 and 8.5.
- D. 7.8 and 10.0.
Correct Answer: A
Rationale: The correct answer is A: 1.8 and 3.5. Pepsin, an enzyme involved in protein digestion, functions optimally in an acidic environment, specifically between pH 1.8 and 3.5. This low pH is necessary for pepsin to break down proteins effectively. Choices B, C, and D are incorrect because pepsin requires a highly acidic environment, ruling out the pH ranges listed in those options.
Which pathogenic bacterium is associated with peptic ulcer disease and gastric cancer?
- A. Lactobacillus.
- B. Bifidobacterium.
- C. H. pylori.
- D. E. coli.
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.