If a cell membrane were composed of only a phospholipid bilayer what properties would it have

Life aint a game 10 is correct. Also the cell would be unable to respond to its environment as this relys on molecules binding to proteins on the cell surface. For the same reason most mechanism of cell signaling not work because the initial step is for a molecule to bind to a receptor. Also no proteins = no receptors = no immune response in white blood cells because this also requires receptors to recognise foreign material.