What gives the cell membrane support?

Answer 1

The plasma membrane is made up of Phospholipids and Proteins.

Phospholipids have a hydrophilic "head" and a hydrophobic "tail". They form into two layers each with the "head" pointing outwards and the "tail" inwards. This means that the hydrophobic "tail" does not have contact with water.

This enables;

lipid-soluble molecules to move into and out of the cell

prevent water-soluble molecules entering or leaving the cell

the membrane to be flexible

The proteins are arranged more randomly and and are embedded in the phospholipid bilayer in two ways:

Extrinsic proteins are on the surface and only partly embedded in it. They provide structural support or act as cell receptors

Intrinsic proteins occur across the plasma membrane and act as carriers to transport water-soluble molecules across the membrane. Some are enzymes.

These proteins provide;

support

a mechanism to transport water-soluble molecules across the membrane

a mechanism to allow active transport to take place by forming ion channels for sodium and potassium (to create the sodium-potassium pump)

The last point about allowing active transport to take place is probably the most important.

Answer 2

Cholesterol.