Which hormone stimulates the gallbladder to contract?
- A. Secretin.
- B. Cholecystokinin (CCK).
- C. Gastrin.
- D. Gastric inhibitory polypeptide (GIP).
Correct Answer: B
Rationale: Cholecystokinin (CCK) is the hormone responsible for stimulating the gallbladder to contract and release bile into the small intestine. Secretin primarily acts on the pancreas to stimulate the secretion of bicarbonate-rich fluid. Gastrin functions in the stimulation of gastric acid secretion, while Gastric inhibitory polypeptide (GIP) plays a role in inhibiting gastric acid secretion and stimulating insulin release.
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After absorption, the end products of carbohydrate and protein digestion enter the:
- A. enterohepatic circulation.
- B. gastrointestinal circulation.
- C. common bile duct.
- D. portal blood system.
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.
What is the term for the action of biting, chewing, and breaking up ingested food into smaller particles?
- A. Peristalsis.
- B. Segmentation.
- C. Metabolism.
- D. Mastication.
Correct Answer: D
Rationale: The correct answer is D, 'Mastication.' Mastication is the mechanical process of chewing that breaks down food into smaller particles. Peristalsis (choice A) is the involuntary constriction and relaxation of muscles in the gastrointestinal tract that moves food along. Segmentation (choice B) is the mixing movement of the digestive system that helps to break down food and mix it with digestive juices. Metabolism (choice C) refers to the chemical processes that occur within a living organism to maintain life.
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.
What is the cause of gas formation in the colon?
- A. Consuming refined foods.
- B. Drinking excess water.
- C. Swallowing air while eating.
- D. Bacterial action on organic compounds.
Correct Answer: D
Rationale: Gas formation in the colon is primarily due to bacterial fermentation of undigested carbohydrates. Choice A, consuming refined foods, is incorrect as gas formation is not directly linked to refined foods but rather undigested carbohydrates. Choice B, drinking excess water, is incorrect as water consumption does not lead to gas formation in the colon. Choice C, swallowing air while eating, is incorrect as this may cause belching but not gas formation in the colon. The correct answer is D because bacterial action on organic compounds, specifically undigested carbohydrates, leads to gas production in the colon.
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.
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