Final answer:
The incorrect membrane function from the list is 'Providing an impermeable barrier' as the correct function of the cell membrane is to be selectively permeable, not impermeable. The item that is not a normal membrane function in a cell is All are not normal.
Step-by-step explanation:
From the list you've provided, the item that is not a normal membrane function in a cell is Providing an impermeable barrier. The plasma membrane or cell membrane is designed to be selectively permeable, and not impermeable.
This means that it selectively allows substances to enter and exit the cell through various mechanisms, such as passive and active transport, maintaining a regulated internal environment.
Functions like compartmentalization, serving as a scaffold for biochemical activity, and providing selective permeability are all essential roles of the cell membrane. The item that is not a normal membrane function in a cell is All are not normal.