The cell membrane (choose all that apply) a. is not a true organelle b. contains and protects the cell c. is made of a double layer of phospholipids d. contains proteins that allow materials to pass through

b. contains and protects the cell

c. is made of a double layer of phospholipids

d. contains proteins that allow materials to pass though

Explanation:

Like skin, the cell membrane is semi-permeable, which means it allows the transfer of some materials, but not others. The membrane keeps harmful materials out and lets beneficial materials in.

The cell membrane is made of special phosphorous molecules and lipids called phospholipids. Phospholipids are shaped like a balloon with two strings. The rounded part of the phospholipid is called the head and the two strings are called the tails. Two layers of phospholipids form the cell membrane. The cell membrane is sometimes called a phospholipid bilayer (bi- meaning two). Embedded within the membrane are special proteins that open and close tiny holes. These holes allow the movement of materials into and out of the cell.