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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The valve that controls the passage of chyme from the small intestine into the cecum is called the:
- A. ileocecal valve.
- B. pyloric valve.
- C. cardiac valve.
- D. hepatic valve.
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.
Feces are composed mainly of bacteria, mucosal cells, mucus, and what else?
- A. bile
- B. enzymes
- C. fiber
- D. chyme
Correct Answer: C
Rationale: The correct answer is 'C: fiber.' Feces are primarily made up of indigestible material, such as fiber. Bile (choice A) is produced by the liver to aid in digestion but is not a major component of feces. Enzymes (choice B) are involved in digestion but are not a significant component of feces. Chyme (choice D) is the semi-fluid mass of partially digested food that moves from the stomach to the small intestine and is not a major component of feces.
What is the process by which proteins are synthesized from the available amino acids?
- A. Gluconeogenesis.
- B. Deamination.
- C. Protein synthesis.
- D. Transamination.
Correct Answer: C
Rationale: The correct answer is C: Protein synthesis. This process involves the formation of proteins from amino acids to support various body functions. Gluconeogenesis (choice A) is the synthesis of glucose from non-carbohydrate sources, not protein synthesis. Deamination (choice B) is the removal of an amino group from an amino acid, not the synthesis of proteins. Transamination (choice D) is the transfer of an amino group from one molecule to another, not the direct synthesis of proteins.
Which enzyme is secreted by the salivary glands?
- A. Pepsin.
- B. Trypsin.
- C. Sucrase.
- D. Amylase.
Correct Answer: D
Rationale: The correct answer is D, amylase. Amylase is an enzyme produced by the salivary glands that initiates the digestion of carbohydrates in the mouth. Pepsin (choice A) is produced in the stomach to digest proteins, trypsin (choice B) is produced in the pancreas to digest proteins, and sucrase (choice C) is produced in the small intestine to break down sucrose. Therefore, choices A, B, and C are incorrect in the context of an enzyme secreted by the salivary glands.
In a low-carbohydrate diet, most of the calories are supplied by:
- A. proteins.
- B. fats.
- C. carbohydrates.
- D. vitamins.
Correct Answer: B
Rationale: In a low-carbohydrate diet, fats become the primary source of calories as carbohydrate intake is restricted. Proteins can contribute to caloric intake but are not the primary source in a low-carbohydrate diet. Carbohydrates are intentionally limited in this diet, so they do not supply most of the calories. Vitamins are essential nutrients but do not provide calories.