What component of membrane contains a hydrophobic region and acts as the primary barrier to most foreign substances?

Phospholipid bilayer is the component of membrane contains a hydrophobic region and acts as the primary barrier to most foreign substances.

Cell division is important to single celled organisms because it allows the cells to reproduce. through cell division, cells make exact copies of themselves. when single celled organisms go through cell division, they make exact copies of themselves which is how they reproduce.