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: Physiology
[{'content': 'Most diffusible ion across membrane - \nSelect and explain. \nA. Na+, B. K+, C. Cl-, D. None', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., Cl?Among the given options, Cl- has lowest permeability coefficient and maximum permeability.Permeability of membraneAs the major middle poion of membrane (core of the membrane) is formed by hydrophobic region of phospholipids, this poion is impermeable to the usual water-soluble substances, such as ions, glucose and urea. Conversely, fat-soluble substances, such as oxygen, carbon dioxide, and alcohol, can penetrate this poion of the membrane with ease.The permeability coefficients of small molecules in the lipid bilayer correlate with their solubilities in nonpolar (hydrophobic) region and thus their permeability.", 'role': 'assistant'}]