Final answer:
The statement is false; cell-surface receptors bind to hydrophilic ligands while intracellular receptors bind to hydrophobic ligands, leading to different mechanisms of action. Option number 2 is correct.
Step-by-step explanation:
The statement that there is no fundamental chemical distinction between signaling molecules that bind to cell-surface receptors and those that bind to intracellular receptors is false. There are distinct differences between these two types of signaling molecules. Cell-surface receptors typically bind to hydrophilic ligands, which cannot easily pass through the plasma membrane.
These receptors facilitate a signaling cascade that leads to a response without the ligand entering the cell. In contrast, intracellular receptors bind to hydrophobic ligands, which can pass through the plasma membrane and enter the cell to directly initiate a response, often by directly influencing gene transcription.