Nokea
Which of these processes occurs in the mouth?
- A. ingestion
- B. mechanical digestion
- C. chemical digestion
- D. all of the above
Correct Answer: D
Rationale: In the mouth, ingestion occurs when food is taken in. Mechanical digestion occurs through chewing and mixing food with saliva. Chemical digestion begins with enzymes in saliva breaking down carbohydrates. Therefore, all processes (ingestion, mechanical digestion, and chemical digestion) occur in the mouth. Other choices are incorrect because they do not encompass all the processes that happen in the mouth.
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Infants' gastric juice contains
- A. nuclease, pepsinogen, lipase
- B. maltase, pepsinogen, rennin
- C. amylase, rennin, pepsinogen
- D. pepsinogen, lipase, rennin
Correct Answer: A
Rationale: The correct answer is A because infants' gastric juice contains nuclease, pepsinogen, and lipase. Nuclease helps in breaking down nucleic acids, pepsinogen is the precursor of pepsin which digests proteins, and lipase digests fats. This combination of enzymes is essential for the digestion of various macromolecules in infants.
Choice B is incorrect because maltase is an enzyme that breaks down maltose (a sugar), which is not typically found in gastric juice. Rennin is an enzyme that helps in digesting milk protein, which is more common in the stomach of newborn mammals, but not in human infants.
Choice C is incorrect because amylase is an enzyme that breaks down carbohydrates and is usually found in saliva, not gastric juice. Rennin and pepsinogen are not typically present in infants' gastric juice.
Choice D is incorrect because while pepsinogen and rennin are enzymes found in gastric juice, lip
The hydrogen ions that form hydrochloric acid of the stomach come from
- A. lactic acid.
- B. carbonic acid.
- C. citric acid.
- D. acetic acid.
Correct Answer: B
Rationale: The correct answer is B: carbonic acid. Carbonic acid is produced when carbon dioxide reacts with water in the stomach, forming hydrogen ions that combine with chloride ions to create hydrochloric acid. Lactic acid (A), citric acid (C), and acetic acid (D) do not directly contribute to the formation of hydrochloric acid in the stomach. Therefore, they are incorrect choices for this question.
The accessory digestive organs include all of the following, EXCEPT:
- A. tongue
- B. liver
- C. pancreas
- D. stomach
Correct Answer: D
Rationale: The correct answer is D, stomach. The stomach is not considered an accessory digestive organ as it is part of the gastrointestinal tract. The accessory digestive organs aid in the digestion process but are not part of the tract itself. The tongue, liver, and pancreas are all considered accessory digestive organs as they play crucial roles in digestion, such as producing enzymes and bile. The stomach's main function is to store and break down food through mechanical and chemical digestion, making it a primary organ in the digestive system rather than an accessory one.
This region of the large intestine has a simple columnar epithelium in its tunica mucosa, smooth muscle in its tunica muscularis, and epiploic appendages attach to its outer surface. This region is called the
- A. cecum.
- B. colon.
- C. rectum.
- D. anal canal.
Correct Answer: B
Rationale: The correct answer is B: colon. The colon is characterized by having a simple columnar epithelium in its tunica mucosa, smooth muscle in its tunica muscularis, and epiploic appendages attached to its outer surface. The cecum (A) is a pouch-like structure at the beginning of the large intestine. The rectum (C) is the final segment of the large intestine before the anal canal (D). The anal canal is lined by stratified squamous epithelium, not simple columnar epithelium like the colon.
The optimum pH for trypsin and chymotrypsin is about
- A. 1-3.
- B. 5-7.
- C. 7-9.
- D. 10-12.
Correct Answer: C
Rationale: The correct answer is C (7-9) because trypsin and chymotrypsin are proteolytic enzymes that function optimally in slightly basic environments. At pH 7-9, these enzymes maintain their structural integrity and catalytic activity. Choices A, B, and D are incorrect because trypsin and chymotrypsin are not acidic enzymes, so pH ranges 1-3 and 10-12 would denature and inactivate them, while pH 5-7 is still on the acidic side, not optimal for these enzymes.