Plasma membrane is made up of

The correct option is Bimolecular lipid layer surrounded by protein layers.

Detailed Explanation:
The plasma membrane, also known as the cell membrane, is a semi-permeable biological membrane that separates the interior of all cells from the outside environment. It plays a critical role in regulating the passage of substances into and out of the cell.

The structure of the plasma membrane can be understood through its main components:
1. Bimolecular Lipid Layer: The core of the membrane is formed by a double layer (bilayer) of lipid molecules, primarily phospholipids. These lipids are amphipathic, meaning they have hydrophilic (water-loving) heads that face the outer and inner aqueous environments, and hydrophobic (water-fearing) tails that face inward, shielding themselves from water.
2. Protein Layers: According to classic membrane structure models (such as the Davson-Danielli model), this central bimolecular lipid core is sandwiched or surrounded on both sides by layers of proteins. These proteins facilitate various cellular processes, including selective transport, cell signaling, and structural support.

Thus, the plasma membrane is structurally described as a bimolecular lipid layer surrounded by protein layers.