Nokea
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.
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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.
The rate of gastric emptying depends on the:
- A. time of day food is consumed.
- B. composition of food consumed.
- C. rate of food consumption.
- D. frequency of eating.
Correct Answer: B
Rationale: The rate at which the stomach empties its contents is primarily determined by the composition of the food consumed. Foods high in fat and protein tend to slow down gastric emptying, while foods high in carbohydrates usually pass through more quickly. Therefore, the composition of food consumed directly impacts the rate of gastric emptying. Choices A, C, and D are incorrect as they do not directly affect the rate of gastric emptying.
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.
Which component of protein contains nitrogen?
- A. Amino group
- B. Carboxyl group
- C. Peptide bond
- D. Side chain
Correct Answer: A
Rationale: The correct answer is the amino group. Amino groups are functional groups found in amino acids, which are the building blocks of proteins. These groups contain nitrogen and are essential for the structure and function of proteins. The carboxyl group (choice B) contains carbon, oxygen, and hydrogen, while the peptide bond (choice C) is a covalent bond formed between amino acids in a protein chain. The side chain (choice D) refers to the unique chemical structure attached to the central carbon of an amino acid and varies among different amino acids, but it does not specifically contain nitrogen.
Ketones are produced when:
- A. carbohydrate stores are depleted.
- B. excess protein is consumed.
- C. protein stores are depleted.
- D. fat stores are depleted.
Correct Answer: A
Rationale: Ketones are produced when the body uses fat for energy due to the depletion of carbohydrate stores. When carbohydrate stores are depleted, the body turns to fat as its primary source of energy, leading to the production of ketones. Excess protein consumption does not directly lead to ketone production. Similarly, the depletion of protein stores or fat stores is not directly related to the production of ketones.