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': 'On weight basis, the percentage of proteins contain in a cell membrane is: \nSelect and explain. \nA. 70%, B. 30%, C. 50%, D. 80%', 'role': 'user'}, {'content': "Answer: C \nExplanation: Proteins are major constituents of membranes (~50% by weight in the plasma membrane). Integral proteins are directly incorporated within the lipid bilayer itself, whereas peripheral proteins exhibit a looser association with one of the two membrane surfaces, paicularly the inner. Ref: (2013). Chapter 2. The Cytoplasm. In Mescher A.L. (Eds), Junqueira's Basic Histology: Text & Atlas, 13e.", 'role': 'assistant'}]