the chemical nature of the membrane
It makes it harder for viruses and free radicals to reach the nucleus.
active transport
A cell's membrane is made up of a phospholipid bilayer which has several protein channels and various other transport mechanisms built in.
It is important because, if the cell membrane was not selectivly permable, we would not be able to do the things today.
It is just a way of keeping some thing out while allowing others to come into the cell. The cell can be destroyed by some things and not by others. It is something like a window screen which allows air to move in and out but keeps out bugs, some of which can be dangerous.
no
The cell membrane is selectively permeable.
The cell membrane is selectively permeable.
The cell membrane is selectively permeable.
the cell membrane
Passive and active transport. Passive transport doesn't require the cell's energy, while active transport does.
Cell membranes are indeed selectively permeable.