Selective Permeability
Selective permeability explained in an easy to understand way:
Imagine trying to control who enters your exclusive party by using a guest list. Just as you only allow certain people who are on the list to enter the party, a cell membrane selectively allows certain substances to pass through while blocking others. In this analogy, the party is like the inside of the cell, the guest list is similar to the selective permeability of the cell membrane, and the guests who are allowed in represent the specific molecules that can enter the cell.
Practice Version
Selective Permeability: The ability of cell membranes to allow some, but not all, substances to pass through selective permeability. Selective permeability means that a cell membrane controls which substances can enter or leave the cell.