How is a cell membrane like a castle wall?

Answer 1

A cell membrane is like a castle wall because it serves as a protective barrier that regulates what enters and exits the cell, much like a wall controls access to a castle. It selectively allows certain substances to pass through while keeping others out, ensuring the internal environment remains stable. Additionally, just as a castle wall can have gates for controlled entry, the cell membrane features proteins that facilitate the movement of specific molecules. This selective permeability is crucial for maintaining the cell's integrity and function.