Textbook Question
Match the letter of the digestive organ shown in the figure with its function.
___ churning occurs here
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23. The Digestive System
The Stomach
Multiple Choice
Which of the following statements about chemical digestion in the stomach are correct:
I. Lipid digestion is begun by enzymes known as lipases.
II. HCl is breaks starches into component monosaccharides.
III. Proteins are denatured by the protein pepsin.
A
I only.
B
I & II.
C
II, & III.
D
I, II, & III.
Verified step by step guidance1
Begin by understanding the role of the stomach in chemical digestion. The stomach primarily focuses on the digestion of proteins, with some activity on lipids, but not carbohydrates.
Examine statement I: Lipid digestion is begun by enzymes known as lipases. This statement is correct because gastric lipase is present in the stomach and begins the digestion of lipids.
Evaluate statement II: HCl breaks starches into component monosaccharides. This statement is incorrect because hydrochloric acid (HCl) in the stomach does not break down starches; it primarily serves to denature proteins and activate pepsinogen into pepsin.
Consider statement III: Proteins are denatured by the protein pepsin. This statement is partially correct. Proteins are denatured by the acidic environment created by HCl, and pepsin further breaks down the denatured proteins into peptides.
Based on the analysis, the correct answer is I only, as statement I is the only fully accurate description of chemical digestion in the stomach.
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