This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: membrane structure and function, Subject name: Biochemistry
[{'content': 'A bilipid layer is most permeable to \nSelect and explain. \nA. Potassiumq, B. Sodium, C. Glucose, D. Urea', 'role': 'user'}, {'content': 'Answer: D \nExplanation: This Flip-flop movement is catalyzed by enzymes. Flippases catalyse the transfer of amino phospholipids across the membrane. Floppases catalyse the outward directed movement which is ATP dependent. This is mainly seen in the role of ABC proteins mediating the efflux of cholesterol and the extrusion of drugs from cells. The MDR (multidrug resistance) associated p-glycoprotein is a floppase. Urea is the most permeable substance across the cell membraneRef: DM Vasudevan, page no: 11', 'role': 'assistant'}]