Bacterial flora in the large intestine do not produce __________.

• A. insulin
• B. vitamin K
• C. short-chain fatty acids
• D. biotin

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the role of bacterial flora in the large intestine. These bacteria are known to synthesize certain substances that are beneficial to the host, such as vitamins and short-chain fatty acids.
2. Step 2: Identify the substances commonly produced by intestinal bacteria. These include vitamin K, which is important for blood clotting, and biotin, a B-vitamin involved in metabolism. They also produce short-chain fatty acids through fermentation of dietary fibers.
3. Step 3: Recognize that insulin is a hormone produced by the pancreas, not by bacteria. It regulates blood glucose levels and is not synthesized by intestinal flora.
4. Step 4: Compare the options given: vitamin K, short-chain fatty acids, and biotin are all products of bacterial metabolism in the large intestine, whereas insulin is not.
5. Step 5: Conclude that the correct answer is the substance not produced by bacterial flora, which is insulin.