Which of the following statements is true regarding the small intestine?
I) The small intestine is divided into three main sections.
II) Much of the chemical digestion in the small intestine is performed by enzymes that are released by the gallbladder.
III) Brush border enzymes are attached to the microvilli.

• A. I & II.
• B. II & III.
• C. I & III.
• D. I II, & III.

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the structure of the small intestine. The small intestine is divided into three main sections: the duodenum, jejunum, and ileum. This makes statement I correct.
2. Step 2: Analyze the role of enzymes in the small intestine. While much of the chemical digestion occurs in the small intestine, the enzymes responsible for this are primarily secreted by the pancreas, not the gallbladder. The gallbladder stores and releases bile, which aids in fat digestion but does not contain digestive enzymes. This makes statement II incorrect.
3. Step 3: Examine the function of brush border enzymes. Brush border enzymes are indeed attached to the microvilli of the small intestine. These enzymes play a critical role in the final stages of digestion by breaking down disaccharides and peptides into absorbable units. This makes statement III correct.
4. Step 4: Combine the analysis of the statements. Based on the evaluation, statements I and III are correct, while statement II is incorrect.
5. Step 5: Conclude that the correct answer is 'I & III' based on the analysis of the small intestine's structure and function.