Why is the cell membrane selectively permeable?
Only substances essential for the survival and functioning of the cell, are allowed to pass into the cell.
Cell membranes are also called selectively permeable membranes, because they are selective in allowing entry of particles into the cell.
This property of selective permeability is important because it ensures the survival of the cell.
Consider an example:
- What were to happen to a human being who would consume anything he comes across?
It would have negative repercussions and it could be fatal/poisonous.
That is the reason we humans only consume a well balanced diet of food items.
Similarly each and every cell within our body needs certain molecules/substances to ensure it can go about its daily activity, these molecules are vital for its survival.
Only molecules essential for the survival of the cell and for vital biological processes , are allowed to pass into the cell.
At the same time certain molecules which are unnecessary / toxic to the cell are barred from entry into the cell.
This is how the cell membrane is selective in nature.