Answer:
What can be noticed about the ligands and their receptor is that the configuration of both coincide, as a key would with its lock, which demonstrates the specificity of a receptor by its ligand.
Step-by-step explanation:
A ligand corresponds to a molecule considered a signal or a messenger, while the receptor is a protein on the cell surface, with the capacity to accept a ligand.
Ligands and receptors constitute pairs that complement each other, so that each receptor can bind to a specific ligand, similar to what happens with a key and a lock.
Once the ligand-receptor complex is formed, changes occur inside the cell, which define a certain effect.