Select the correct statement from the following regarding cell membrane. (a) Na + and K + ions move across cell membrane by passive transport. (b) Proteins make up 60 to 70% of the cell membrane. (c) Lipids are arranged in a bilayer with polar heads towards the inner part. (d) Fluid mosaic model of cell membrane was proposed by Singer and Nicolson.
Option D is correct. According to the fluid mosaic model of cell membrane structure proposed by Singer and Nicolson (1972) plasma membrane contains about 50–60% proteins and 50–40% lipids. Lipids form a bilayer with hydrophilic heads pointing outwards. Cell membrane allows transport of some molecules by passive transport e.g., water, neutral solutes while some are transported actively e.g., Na + /K + pump.
