Cholecystokinin (CCK) is produced in the:
- A. duodenum.
- B. stomach.
- C. pancreas.
- D. liver.
Correct Answer: A
Rationale: Cholecystokinin (CCK) is produced in the duodenum, not the stomach, pancreas, or liver. It is released in response to the presence of food in the duodenum, where it plays a crucial role in regulating digestive processes by stimulating the release of bile from the gallbladder and enzymes from the pancreas. Therefore, the correct answer is the duodenum (Choice A). Choices B, C, and D are incorrect because CCK is not produced in the stomach, pancreas, or liver.
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What substance activates pepsinogen to pepsin?
- A. Bile
- B. Gastrin
- C. Secretin
- D. Hydrochloric acid
Correct Answer: D
Rationale: The correct answer is D: Hydrochloric acid. Hydrochloric acid in the stomach plays a crucial role in converting pepsinogen into its active form, pepsin, which is necessary for digesting proteins. Bile (Choice A) is involved in the emulsification of fats, not in the activation of pepsinogen. Gastrin (Choice B) is a hormone that stimulates the secretion of gastric acid but does not directly activate pepsinogen. Secretin (Choice C) is a hormone that regulates the pH of the duodenum but is not responsible for the activation of pepsinogen.
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.
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.
The process of breaking down body protein into amino acids for energy is known as:
- A. Deamination.
- B. Transamination.
- C. Transcription.
- D. Catabolism.
Correct Answer: D
Rationale: The correct answer is D: Catabolism. Catabolism involves the breakdown of body proteins into amino acids to be used as energy when there is an inadequate dietary intake. Choices A and B, deamination and transamination, involve the removal and transfer of amino groups, respectively, but not the breakdown of body proteins. Choice C, transcription, is a process in genetics where DNA is used to create mRNA, not related to breaking down body proteins.
What are the major sources of energy for the body?
- A. Proteins and fats.
- B. Carbohydrates and fats.
- C. Proteins and carbohydrates.
- D. Vitamins and minerals.
Correct Answer: B
Rationale: The correct answer is B: Carbohydrates and fats. Carbohydrates are the body's primary and most efficient source of energy, providing fuel for daily activities. Fats are also a significant energy source, especially during times of prolonged or intense exercise. Proteins are primarily used for building and repairing tissues, not as a major energy source. Vitamins and minerals are essential for various bodily functions but do not serve as direct sources of energy.