Which of these digestive enzymes breaks down fats?

Correct Answer: B

Rationale: The correct answer is B: lipase. Lipase is the enzyme responsible for breaking down fats into fatty acids and glycerol. Amylase (A) breaks down carbohydrates, trypsin (C) breaks down proteins, and pepsin (D) also breaks down proteins but in the stomach. Lipase specifically targets fats in the small intestine, aiding in their digestion and absorption. Therefore, lipase is the correct choice for breaking down fats, making it the most suitable answer among the options provided.

Correct Answer: C

Rationale: The correct answer is C: Digestion of lipids is not a function of saliva. Saliva primarily aids in cleaning the mouth by washing away food particles, killing bacteria with its antibacterial properties, and facilitating speech by lubricating the mouth and throat. Digestion of lipids primarily occurs in the small intestine with the help of enzymes like lipase. Salivary amylase, found in saliva, assists in breaking down carbohydrates, not lipids. Therefore, digestion of lipids is not a function of saliva.

Correct Answer: D

Rationale: The correct answer is D: Sucrose. Diseases that reduce pancreatic enzyme secretions typically do not affect the digestion and absorption of sucrose because sucrose is primarily broken down in the small intestine by sucrase, an enzyme produced by the intestinal lining, not the pancreas. Animal proteins (choice A) and plant proteins (choice B) require pancreatic enzymes like trypsin and chymotrypsin for digestion; plant lipids (choice C) require pancreatic lipase for digestion. Therefore, choices A, B, and C would be affected by reduced pancreatic enzyme secretions, unlike sucrose.

Correct Answer: B

Rationale: The correct answer is B: Diseases of the inner ear. Vomiting is primarily controlled by the vomiting center in the brainstem, which responds to various stimuli such as irritation of the duodenal mucosa (Choice A), microbial toxins in the blood (Choice C), and severe exercise (Choice D). Diseases of the inner ear do not directly trigger the vomiting reflex, making Choice B the correct answer.

Correct Answer: A

Rationale: The correct answer is A: upper gastrointestinal bleeding. Melena is black, tarry stool resulting from the digestion of blood in the gastrointestinal tract. This typically occurs in the upper GI tract due to the longer transit time, allowing the blood to be digested. Lower GI bleeding usually presents as bright red blood in the stool or maroon-colored stool. Therefore, melena is a specific indicator of upper GI bleeding. Choices B, C, and D are incorrect because melena specifically points to upper GI bleeding, not lower GI bleeding or both.