Answer: Lipid by-layer
Step-by-step explanation:
The receptors of the ligand are found embedded on the plasma membrane of the cell. These receptors binds with the ligand and response is generated.
The receptors can be found on the plasma membrane and these are the cell surface receptors.
They help in the cell signaling by receiving the extracellular molecules. The cell response is generated when the extracellular molecules get attached to cell surface receptor.