This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
[{'content': 'Which of the following cannot be degraded by colonic microorgamismic flora and gastrointestinal enzymes? \nSelect and explain. \nA. Pectin, B. Lignin, C. Cellulose, D. Glucose', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Lignin is a highly branched polymer composed of phenol units with strong intramolecular bonding. It can neither be digested by gastrointestinal enzymes nor fermented by colonic microorganisms. Cellulose, Hemicellulose and Pectins are plant components that cannot be digested by gastrointestinal enzymes but can be fermented by colonic microorganisms.', 'role': 'assistant'}]