Which statement about the large intestine is true?

• A. Contains microorganisms which assist in digestion
• B. Produces bile
• C. Primary site of digestion
• D. Gas exchange

Answer: (A)

Microorganisms in the large intestine help digestion. A diverse community of bacteria ferments leftover plant fibers, producing short‑chain fatty acids that nourish the cells lining the colon and gases that are expelled. These microbes also synthesize certain vitamins, such as vitamin K and some B vitamins, contributing to the gut’s metabolic activities. The large intestine’s main roles include absorbing water and electrolytes and forming solid waste, rather than carrying out the primary breakdown of food. Bile is produced by the liver and released into the small intestine, not the large intestine. Most digestion occurs in the small intestine, where enzymes break down proteins, fats, and carbohydrates. Gas exchange happens in the lungs, not in the digestive system.