Which one of the following is not a constituent of cell membrane?

In terms of permeability,the cell wall and plasmalemma are:

Structure and function are correlatable in living organisms. Can you justify this by taking the plasma membrane as an example?

The nature of the plasma membrane is:

The plant cell cytoplasm is surrounded by both cell wall and cell membrane. The specificity of transport of substances is mostly across the cell membrane,because $..........$

Keeping in view the 'fluid mosaic model' for the structure of the cell membrane,which one of the following statements is correct with respect to the movements of lipids and proteins from one lipid monolayer to the other (described as flip-flop movement)?