Nokea
The release of gastric secretions is stimulated by nerve and hormonal stimuli and the:
- A. ingestion of water.
- B. swallowing reflex.
- C. presence of food in the stomach.
- D. closing of the pyloric sphincter.
Correct Answer: C
Rationale: The correct answer is C: 'presence of food in the stomach.' Gastric secretions are stimulated when food enters the stomach, triggering nerve and hormonal responses. This process prepares the stomach for digestion. Choices A, B, and D are incorrect because ingesting water, swallowing reflex, and the closing of the pyloric sphincter do not directly stimulate the release of gastric secretions.
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Where does gluconeogenesis occur?
- A. Muscles.
- B. Pancreas.
- C. Liver.
- D. Spleen.
Correct Answer: C
Rationale: Gluconeogenesis mainly occurs in the liver. It is a process where glucose is synthesized from non-carbohydrate sources such as amino acids and glycerol. The liver is the primary site for gluconeogenesis due to the presence of key enzymes and substrates required for this process. Muscles do not play a significant role in gluconeogenesis, making choice A incorrect. The pancreas is involved in the regulation of blood sugar levels through insulin and glucagon but is not the primary site for gluconeogenesis, so choice B is incorrect. The spleen is not a major organ involved in glucose metabolism, making choice D incorrect.
How many different amino acids make up human proteins?
- A. 9
- B. 13
- C. 15
- D. 20
Correct Answer: D
Rationale: The correct answer is D: 20. There are 20 different amino acids that combine to form proteins in the human body. Each amino acid has a unique side chain that determines its properties. Choices A, B, and C are incorrect as they do not represent the total number of different amino acids found in human proteins.
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 substance acts as an emulsifier and helps absorb digested fat?
- A. bile
- B. trypsin
- C. lipase
- D. cholecystokinin (CCK)
Correct Answer: A
Rationale: The correct answer is A: bile. Bile acts as an emulsifier, breaking down fats into smaller droplets to aid in digestion and absorption. Trypsin is a digestive enzyme that acts on proteins, not fats. Lipase is an enzyme that breaks down fats, but it doesn't act as an emulsifier. Cholecystokinin (CCK) is a hormone that stimulates the release of digestive enzymes, including lipase, but it is not directly involved in emulsification.
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.